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[IMPERIAL PRIZE ESSAY.] 
 
 EXPERIMENTAL 
 
 DIPHTHERIA 
 
 BY 
 
 DR. OTTO HEUBNER, 
 
 A. O. Prof, of Medicine, University Leipzig. 
 
 )° to. 
 
 2- 
 
 TRANSLATED BY 
 
 H. G. BEYER, M. D., M. R. C. S. 
 
 P. A. Surgeon U. S. Navy, Curator Materia Medica, U. S. National Museum. 
 
 FEB 23 
 
 fa*?**-*? 
 
 DETROIT 
 GEO. S. DAVIS, MEDICAL PUBLISHER. 
 
Copyright by 
 GEORGE S. DAVIS, 
 
 1885. 
 
PKEFAOE. 
 
 The work which I am about to present to the medical profession in the 
 following pages, has achieved the great honor of being awarded the prize 
 offered by her majesty, the Empress-Queen Augusta, for the best research on 
 diphtheria. 
 
 No one can be more fully aware than the author that he has fallen 
 short of the end sought by the giver of the prize, viz., the discovery of a 
 remedy for diphtheria. But in seeking for such a remedy, the following inves- 
 tigations had their origin. 
 
 Having lost many a battle with this disease so terribly destructive to 
 infants, I have frequently asked myself if the received opinions upon which 
 our present treatment is based are correct, and here I encountered grave 
 doubts. I was at last moved to make the attempt of looking deeper into the 
 nature of diphtheria. 
 
 But few are the steps, and limited are the results, which can be taken by 
 a single individual, in a pursuit like this. It must be left to the judgment of the 
 reader whether or no my researches have brought us nearer the truth, or have 
 expanded our views of it. What I here present is merely the result of my 
 experimental research. My views upon the nature and treatment of human 
 diphtheria — partly the result of these experiments, partly the result of clinical 
 thought aroused by them — I do not give here because I have not yet had an 
 opportunity to put them into practice with that accuracy which necessarily applies 
 to all experimental research. I reported them in brief in the Transactions of 
 the Second Medical Congress, at Weisbaden, and refer those who are inter- 
 ested in them to the reports of this congress, which will shortly appear in 
 print.* 
 
 Before one attempts by artificial means to produce in an animal, a disease 
 which is calculated to throw light upon analogous processes in the human sub- 
 ject, it is necessary, above all, to first have as clear and definite a conception as 
 possible of the human disease itself. This necessity becomes particularly ap- 
 parent when we reflect on the manifold views and varying importance which 
 have been attached to the terms diphtheritis and diphtheria, by individual med- 
 ical authors in the last few decades. 
 
 This denomination, which, since Bretonneau's time, has been given by 
 all physicians to an acute general disease, did not primarily originate in a 
 desire to express the nature of the disease through which the entire organism 
 
 * See Appendix. 
 
IV PREFACE. 
 
 is involved in a feverish condition, in which the heart, the kidneys, the spleen 
 and nervous system take part, but in the fact that a peculiar local process, the 
 formation of fibrinous membrane on mucous and granulation surfaces, became 
 very characteristic, and the presence of which in certain localities is alone suffi- 
 cient, in a mechanical way, to terminate life. 
 
 In the course of time, however, cases occurred, in which the formation of 
 false membranes did not constitute so prominent a character of the disease, and 
 was not in itself dangerous to life, but in which everything pointed rather to 
 the existence of a grave constitutional infection, involving the entire human 
 organism in a condition of blood-poisoning; when in addition to this a number 
 of experiments, which were made, seemed to prove that by inoculation of certain 
 matters from a diseased human being, diseases, including diphtheria, could be 
 transferred to animals, the importance of the term diphtheria gradually lessened, 
 and began to be more and more restricted to the constitutional condition which 
 always obtains in Bretonneau's disease. And when anyone now speaks of diph- 
 theria of the cornea, for instance, no thought at all is given to Bretonneau's 
 membrane. 
 
 It is, however, evident that both elements, the disturbance of the entire or- 
 ganism as well as the local process of the formation of a false membrane, must 
 be taken into consideration as essential factors in our disease. The problem 
 of producing an analogous disease in animals cannot be considered as solved, 
 if the. artificially produced disease in, animals is only one of general infection, 
 and in which, only exceptionally, a false membrane makes its appearance, 
 which latter is only rarely wanting in the disease as it occurs in the human 
 subject. 
 
 But in view of the difficulty of tracing out the causes of diphtheria we 
 must still go a step further in the analysis of our conception of the disease. If 
 Bretonneau's disease is — according to the views of the majority of phy- 
 sicians — a specific one caused invariably by the same poison, we must also 
 take into consideration the fact that Bretonneau's diphtheria, that is, the forma- 
 tion of fibrinous exudation in and upon mucous membranes, does not exclu- 
 sively belong to Bretonneau's disease. On the contrary, we find it accompany- 
 ing a great number of diseases, which according to our clinical and etiological 
 views, have nothing in common with genuine diphtheria. Prominent among 
 these stands dysentery, which offers a condition of things in the large intestine, 
 which, anatomically, represents diphtheria. We find, furthermore, genuine 
 diphtheria of the throat in scarlet fever, fibrinous exudation in different mem- 
 branes in cases of small pox, measles, in the typhoid stage of cholera, in 
 typhoid fever, on granulating surfaces, on the mucous membranes of the 
 bladder, in certain cases of cystitis, even on the mucous membranes of the gall 
 bladder, etc. 
 
 From these anatomo-pathological facts we may draw the conclusion 
 that the formation of a false membrane is not peculiar to genuine 
 diphtheria, but that its poison, in common with different other poisons, pos- 
 sesses the property of producing the peculiar disease of the mucous membrane. 
 It is, therefore, to be regarded as highly probable that the immediate causes of 
 
PREFACE. V 
 
 the diphtheritic diseases of mucous membranes are everywhere the same, 
 but that very different morbific agents are capable of calling into existence 
 these immediate causes, in perhaps very many different ways. 
 
 It thus follows that the problem of experimentally tracing out the causes 
 of diphtheritis must necessarily be along two different lines of investigation, the 
 one of which must be directed to the conditions necessary for the production 
 of the diphtheritic membrane, the other, to the conditions of the general diph- 
 theritic infection; in other words, to the diphtheritic poison and its relations to 
 the local process of the formation of false membranes. This is the method of 
 research which has been followed out in these investigations. 
 
 THE AUTHOR. 
 
 Leipzig, May nth, 1883. 
 
I. The Experimental Production of Diphther- 
 itic Disease in Mucous Membranes. 
 
 The attempt to produce the anatomical changes peculiar to 
 diphtheria by artificial means, has, as is well known, been frequently 
 made. After Treitz, it was particularly Oertel and Weigert, who 
 undertook a most careful investigation of the croupous exudation 
 which follows the application of caustics to the trachea of the rabbit, 
 and they have shown that this artificially produced tracheal croup 
 presents the anatomical and chemical characteristics which are 
 found in the exudations upon the surface of mucous membranes in 
 diphtheria. After this was done Weigert proceeded to study the pro- 
 cesses which lead to the formation of an artificial croupous mem- 
 brane, and he succeeded in clearly tracing out the various steps 
 which are necessary to the production of this fibrinous membrane, 
 thus creating the term coagulation-necrosis, meaning thereby a pro- 
 cess of dying under coagulation. Although, doubtless, this was a 
 step in the right direction, it was also true, notwithstanding the 
 identity of the product in the animal with that of man, that the 
 method of the artificial production of this membrane was in no wise 
 analogous to the pathological processes as they occur in the human 
 subject. Apart from accidental cauterizations of the epithelium of 
 mucous membranes, by which, of course, croupous membranes may 
 also arise in the human subject, the process of the formation of 
 croupous membranes in man is not called forth by such injuries as 
 the action of caustics, which may be compared to a poison possess- 
 ing the property of destroying the epithelium; and the idea that 
 perhaps bacteria exercise an analogous influence over the epithelium, 
 remains for the present a mere hypothesis. 
 
 Thus, even after Weigert's work, there remained to be discov- 
 ered a method for producing the diphtheritic process in the mucous 
 membrane of an animal, which one might well imagine to re- 
 semble the process obtaining in the human organism. In this I 
 was successful upon the following grounds: 
 
EXPERIMENTAL DIPHTHERIA. 
 
 Cohnheim had noticed that a temporary interruption of the cir- 
 culation in certain tissues, as the ear of the rabbit, the kidney and 
 the testicle was followed by a series of inflammatory processes, 
 which under considerable swelling and the formation of infarctions 
 within the tissues, finally lead to .necrosis. Litten thereupon under- 
 took the further study of these effects, which were produced by a 
 temporary interruption of the arterial blood stream upon the tissues 
 of the kidney, and observed among other results, that the epi- 
 thelia of the kidney had undergone the same peculiar process of 
 dying which Cohnheim and Weigert designated coagulation- 
 necrosis. 
 
 If such an effect could be produced upon renal epithelia, it was 
 also to be supposed that the pathological process which is indicated 
 by the term diphtheria, and which is nothing else than a coagulation- 
 necrosis of the epithelium of the mucous membranes, and even of 
 the mucous membrane itself, might also be produced, under analo- 
 gous conditions, on mucous membranes. 
 
 Diphtheria being nothing more nor less than such a coagulation- 
 necrosis of mucous tissue, it was to be supposed that the mucous 
 membrane, under analogous conditions, would undergo the same 
 peculiar changes as the renal epithelia. 
 
 This supposition was fairly realized after the proper object for 
 experimentation had been discovered. 
 
 For, above all, it was necessary to find a tract of mucous mem- 
 brane to which this method could be applied, and in which it was 
 possible that the part could be shut out from the general circulation 
 for a given time. It was hopeless to entertain such an idea with 
 regard to the mucous membrane of the throat. The uvula would 
 have answered the purpose very well indeed, but neither dogs nor 
 rabbits possess uvulae. Some experiments made on the third tarsal 
 cartilage of the rabbit failed to give any clear results, probably on 
 account of the interruption of the circulation not being complete. 
 
 At the suggestion of Professor Cohnheim, to whom I am very 
 much indebted, I chose the urinary bladder of the rabbit. . This 
 organ answered our purpose completely. The fundus of the blad- 
 der of the rabbit is supplied with blood by two arteries, which run 
 up on either side from the neck; the blood is returned by veins pur- 
 suing a similar course to that of the arteries. If we surround the 
 bladder of the living animal with a ligature, in such a manner that 
 
EXPERIMENTAL DIPHTHERIA. 
 
 the ligature will come to lie near the neck, if possible above the 
 opening of the ureters, the circulation in the fundus of the bladder 
 will be completely arrested. For this organ, which projects into the 
 abdominal cavity, being covered by peritoneum, does not receive 
 any blood supply in a collateral way, and a sudden arrest in the cir- 
 culation after the above method, is brought about. If the ligature 
 is removed after a certain length of time, the circulation is restored 
 in those vessels which are free from thrombi. 
 
 By this method we do not produce the so-called anaemia or 
 ischaemia, for by means of the ligature the blood-current in both veins 
 and arteries, is stopped at the same time. What really takes place is 
 the sudden arrest of the entire blood column contained within the 
 ligated organ. In this the method more closely resembles that of 
 Cohnheim than that of Litten. A certain share of what happens, 
 after the ligature has been removed, must necessarily be ascribed to 
 the influence of the nervous system in these as well as in Cohn- 
 heim's experiments. What that share is has already been mentioned, 
 in a very clear and concise manner, by Cohnheim. 
 
 This complicating circumstance need not be taken into consid- 
 eration, inasmuch as it is the immediate conditions, not the remote 
 ones, that determine the affection of the mucous membrane, which 
 we are trying to study. At any rate, if it succeeded in producing, 
 in this manner, the anatomical conditions of diphtheria, a method is 
 found by which the portion to be experimented on remained per- 
 fectly intact, and is subjected to none but functional disturbances in 
 such a way as they may well occur in the human subject. We will 
 see from what follows that this proved surprisingly successful. 
 
 The operation is simple, and must be made under antiseptic pre- 
 cautions. The rabbit is tied with his back to the table; an incision 
 about three or four centimetres long, and beginning immediately 
 above the symphysis is made in the linea alba. The extent of it 
 must be just sufficient to "admit of the protrusion of the bladder, 
 which is generally filled ; it must not be larger, in order that the 
 protrusion of the intestines and uterus may be prevented. 
 
 The fundus of the bladder carefully drawn out, under a con- 
 stant carbolic acid spray, is quickly ligated, and returned into the 
 abdominal cavity. Everything is done in a few minutes. The 
 wound is then closed with several sutures, one end of the ligature, 
 however, protruding from the wound in order to facilitate the second 
 
EXPERIMENTAL DIPHTHERIA. 
 
 step in the operation, which is to cut the ligature without being 
 obliged to draw the entire bladder out from the abdominal cavity. 
 After this the skin of the abdomen is sewed up, and the animal set 
 at liberty. 
 
 At the end of two hours — the uniform duration of the arrest of 
 the blood current — as many sutures are removed as are necessary 
 for the removal of the ligature; the ligature is pulled out, and now 
 the abdominal walls are most carefully closed with numerous sutures, 
 under the carbolic acid spray. ■ 
 
 If this operation is carried out under antiseptic precautions, it 
 will be very successful and the wound will heal without the for- 
 mation of any pus. It will, however, in some cases, happen that a slight 
 pus-cavity forms between the skin and muscle of the abdominal 
 parietes. 
 
 In two out of twenty-five operations septic infection occurred, 
 and in both instances I had been assisted by a friend who was 
 doing a great deal of dissecting at the time. 
 
 I will now give a detailed description of the experiments: 
 
 Experiment I. — A very 'strong rabbit was operated upon on 
 November 23d, 1880, in the manner indicated above. The ligature 
 around the fundus of the bladder was kept on for two hours, and 
 thus complete arrest of circulation brought about for that period. 
 
 On the following day the animal was very well, ate well and had 
 no fever, the temperature being 38. 9 C. About 40 c. c. of urine 
 which was collected gave 1-5 vol. albumen, and contained some blood 
 corpuscles, epithelia, granules, etc. No pus. 
 
 November 25th. Temperature 39. 6° C. Animal ate well; copious 
 movement of normal stool. Urine about 10 c. c. with 1-4 vol. of 
 albumen; is of darker color, contains peculiar sharp-edged epithelia 
 not unlike those which are characteristic of diphtheria, epithelia 
 containing blood pigment, blood corpuscles, some leucocytes, mucus, 
 and a finely fibrinous coagulum within which are enclosed several 
 blood-corpuscles. 
 
 November 26th. Temperature 39.5°C. Animal ate but little, 
 drank a great deal, otherwise general health seems good. Urine 
 collected amounted to 25 c. c, contained 1-3 vol. albumen, much 
 mucus, a few round cells, and clusters of epithelia. Some very well- 
 preserved epithelia hang together with some peculiar non-nucleated 
 " schollen." 
 
EXPERIMENTAL DIPHTHERIA. 
 
 At 3:30 p. m. on same day, that is, at the end of the third day 
 after the operation, the animal was killed with chloroform. 
 
 The post mortem was made immediately. — Between skin and 
 muscle of the abdominal wall and near the seat of the operation, a 
 small, flat pus-cavity was discovered. Muscular walls healed perfectly. 
 Peritoneum shows no trace of inflammation. Anterior wall of bladder 
 sticking loosely to abdominal wall; no pus. # 
 
 The fundus of the bladder is of a dark-red appearance exter- 
 nally, very much swollen, its walls considerably thicker and stiffen 
 On opening the bladder, the mucous membrane above the ligature, 
 shows marked swelling, a dark-red discoloration, and is dotted all 
 over with ecchymotic spots ; contrasts very strongly with the part 
 below the ligature. 
 
 On close examination and after spreading out the entire bladder 
 fundus, it was found to consist of hyperaemic, hemorrhagic, and mark- 
 edly swollen tissue. Within this region, however, we find a small scar 
 of the size of an old three-penny piece, which shows much greater 
 swellings and by its yellow color is easily distinguishable from the 
 rest of the surrounding membrane, macroscopically presenting a pic- 
 ture very much like what is seen in a diphtheritic patch. Only a 
 very small part of the fundus, to the extent of 1-2 sq. cm., is a yellow, 
 firm piece of necrotic tissue. 
 
 Thus, it was found, that by an arrest of the normal functions of 
 the circulation in the organ, we had produced a condition of things, 
 much resembling that of a diphtheritic exudation. Before we now 
 enter into the histology of the resulting tissue, we propose to follow 
 out in more detail the chronological sequence of the entire develop- 
 ment of the process and to give for each one of the different stages, 
 both its macroscopical and its microscopical appearances. 
 
 (a) If an animal, upon which the above operation has been per- 
 formed, be killed within the first twenty-four hours, or towards the 
 end of the first day after removing the ligature, the bladder presents 
 the following characteristic appearances: 
 
 That part of the bladder which is immediately below the ligature 
 is intensely injected; this extreme vascularity gradually fades away 
 towards the mouth of the urethra. In the part above the ligature 
 necrosis is observed to have set in at points, extending to the entire 
 thickness of the wall, where the circulation has not been restored. 
 In very successful cases, however, no necrosis is generally found, or 
 
EXPERIMENTAL DIPHTHERIA. 
 
 exists to only a very slight extent. The larger part of the wall of the 
 bladder is considerably swollen, and has sometimes a reddish-gray, 
 sometimes a dark-red haemorrhagic appearance. This swelling is 
 mainly due to an cedematous condition of the submucosa, the 
 mucous membrane itself having actually no room for accommodating 
 itself to this changed condition of things and is thrown into numer- 
 ous folds and rugae. If the bladder is left to itself a certain length 
 of time, these folds, rugae and elevations of the mucous membrane, 
 go down and eventually disappear, a great deal of fluid, at the same 
 time oozing from the edges of the incision, thus proving that the 
 swelling is due to an accumulation of fluid within the walls of the 
 bladder. If the bladder in this condition is placed in absolute alco- 
 hol or is boiled, the fluid is retained and the exact seat of it can be 
 studied ; this of course cannot be done without the occurrence of a 
 good deal of shrinkage. Very fine pictures are also obtained from 
 frozen sections. 
 
 In- very fine sections the following may be made out: The 
 thickness of the bladder wall has increased from five to even ten 
 times its normal dimension. The principal part of this thickening is 
 found in the submucosa. The meshes of the submucous layer are 
 distended with fluid and the mucous and muscular, as well as serous 
 layers, are also in a succulent, loose condition. The fluid, after it has 
 undergone coagulation by absolute alcohol, exhibits a very fine 
 fibrous network with more or less larger and smaller meshes. By 
 boiling according to Koch's method, this network reveals itself as a 
 homogeneous substance causing slight refraction of the rays of 
 light; in frozen preparations it has a granular appearance. It is 
 easily and very intensely stained by eosin. It is obvious, then, that 
 we have here to do with a serum rich in coagulable albumen. 
 
 The bloodvessels (veins and capillaries) throughout the entire 
 bladder, more particularly in the mucosa close up to the. epi- 
 thelial covering, and also in the serosa, are very much distended 
 and crowded with blood corpuscles. In a number of places may 
 be seen a marginal zone of white blood corpuscles, which like a 
 wreath surrounds the lumen of the vessels. All along the blood- 
 vessels and also at a certain distance from them, there can be seen 
 an extra-vascular cell infiltration which is .very dense in places where 
 the tissue is less cedematous, and less dense where the oedema is more 
 marked. The nuclei of these cells, which are apparently nothing 
 
EXPERIMENTAL DIPHTHERIA. 
 
 else than white blood corpuscles, are everywhere perfectly stained, 
 even in places where the oedema is most pronounced. But the red 
 corpuscles have also escaped from their vessels in great numbers. 
 They lie scattered in the most superficial layer of the submucosa, in 
 the mucosa, and to a certain extent also in between the epithelial 
 cells partly in the form of ecchymoses and hsemorrhagic infiltrations, 
 and partly as single cells. 
 
 More particularly interesting is the appearance of the epithelium 
 of the mucous membrane itself, which, normally, in the rabbit also, 
 is a stratified epithelium. It is distinctly loosened in its connections 
 and the most superficial layers have become distinctly swollen and 
 enlarged. A few of those swollen cells contain vacuoles and 
 others present a kind of corroded appearance, somewhat after the 
 manner that Wagner has described as fibrinous degeneration of the 
 epithelium, but wanting in the peculiar lustre of the prickles. 
 Such formations are particularly apparent in boiled prepara- 
 tions The albuminous fluid between and on the surface of the 
 epithelial cells is coagulated and intimately adheres to them. Such 
 masses are stained uniformly red in eosin, but nuclei can no longer 
 be distinguished in them, and even in the main mass of epithelia the 
 nuclei are only stained with difficulty.* 
 
 Fig. i, right half, and Fig. 2, represent pretty well the appear- 
 ances just described. Fig. 1, is from an animal killed on the 
 second day after the operation ; and Fig. 2, from one killed on 
 the first day. The latter preparation is taken from a piece of boiled 
 tissue. The staining is with eosin and gentiana violet. In Fig. 1, one 
 can recognize the loosened and oedematously enlarged epithelial cells 
 with faintly stained nuclei among the mucous and submucous layers 
 in like condition. In between them there are haemorrhages pro- 
 ceeding from a neighboring bloodvessel. 
 
 Fig. 2, represents a portion of epithelial tissue under a stronger 
 magnifying power, with effused liquid between the cells. 
 
 (/?) If the animal is allowed to live somewhat longer, say from 
 thirty to thirty-six hours, we find essentially the same condition 
 of things as in the previous case. But now a certain number 
 of little swellings can be noticed, generally of a red or reddish- 
 black color, which do not collapse when the watery fluid is allowed 
 to run off from the wound of the incised bladder. These swellings 
 consist, therefore, of a congealed exudation. The histological in- 
 
EXPERIMENTAL DIPHTHERIA. 
 
 vestigations of such places show that they consist of an accumula- 
 tion of homogeneous masses, and partly also of the debris of white 
 blood corpuscles, but for the greater part are composed of red blood 
 corpuscles, in the mucous as well as the submucous layers. Stain- 
 ing with Bismarck brown or gentian as violet is unable to reproduce 
 the original connective tissue framework in this mass of homo- 
 geneous infiltration, but everywhere we find exudations through 
 which can be traced aggregate masses of detritus in the place of the 
 former connective tissue. 
 
 (Vide Fig. i, left half. In it one recognizes that the entire 
 mucous membrane, including submucous tissue, has been transformed 
 into a substance which is stained red with eosin; scattered rather 
 uniformly all through it, there is a rich nuclear detritus which is 
 stained blue, and which contrasts beautifully with the right side of 
 the picture in which the original normal structure is retained. It is 
 a complete diphtheritic patch.) 
 
 The epithelium is wanting in those consolidated little swellings 
 above mentioned, or has become resolved in them. On the whole it 
 is still present even here, but all the cells are swollen up. The 
 nuclei of the superficial layers, take but a very faint stain or are only 
 partially stained, and have a folded appearance. The protoplasm 
 of the cells contains vacuoles and is shaggy. All the rest of the 
 tissue is as in the case (a). 
 
 (c) If the animal is kept alive forty-eight hours after the opera- 
 tion, one perceives between the hsemorrhagic, cedematous swellings 
 which cover the entire mucous surface, some few small patches of a 
 yellowish color and quite firm. These are found sometimes in the 
 neighborhood of the place of the ligatures, and sometimes they can 
 be more easily followed towards the fundus and can always be 
 differentiated from the surrounding portions by their color and 
 peculiar lustre. The yellowish patches consist uniformly of rigid, 
 congealed, dead tissue, as in the second case, only that the discolora- 
 tion is still more marked. Nowhere can a single definite nucleus be 
 found, and even the nuclear detritus is but very scanty. There is no 
 trace of any epithelium to be found on the surface. The tissue can 
 be stained intensely red with eosin. Nearer the muscularis a larger 
 quantity of stainable nuclei may be found. These cells, however, 
 come from the dilated vessels of the submucous layer, which like a 
 wreath surrounds the dead tissue. 
 
EXPERIMENTAL DIPHTHERIA. 
 
 In this stage one can study the origin of such patches in a few 
 places. Here and there is a narrow zone of submucous tissue 
 without nuclei, and rigid. When such a zone is followed out one 
 suddenly comes upon a very copious extravasation of red and white 
 corpuscles, surrounding some still well preserved dilated blood-ves- 
 sels. This extravasation can be followed downwards into the deeper 
 layers of the submucosa, and upwards into the deeper epithelial 
 layers, thus forming a sort of biconcave infiltration on the borders 
 of the mucous membrane. 
 
 The epithelium, when it is still well enough preserved, on those 
 portions, for example, which have not suffered too much, still shows 
 a copious oedema; every single cell is twice or three times larger, 
 every still stainable nucleus is surrounded by a light halo, which 
 separates it from the surrounding protoplasm. Here and there 
 the upper layers of the epithelium have fallen off. Frequently 
 dense infarctions of the entire epithelial stratum into blood cor- 
 puscles are met with, and also in certain places a congealed mass is 
 found. 
 
 (d) If the animal is killed seventy-two hours after the removal 
 of the ligature, we meet, macroscopically, with the picture already 
 described in connection with Experiment I., and know now that the 
 transformation of the mucous surface into a rigid, pale yellow, 
 voluminous mass, found now more extensively, is nothing else but a 
 far wider extension of the coagulation-necrosis of the epithe- 
 lium of the mucosa and sub-mucosa, which already commenced 
 on the first and second day. For, if we again examine these infiltra- 
 tions of the mucous membrane, which resemble diphtheritic patches, 
 we meet here, as well as elsewhere, with the same structureless, rigid, 
 dull-shining mass of tissue, deeply stainable in eosin, but in no wise 
 showing the presence of living nuclei. The only difference that 
 exists is one of extent in depth as well as in breadth, but not in kind; 
 and now we find that not only the mucous and sub-mucous layers 
 are implicated, but also the muscular and serous layer of the blad- 
 der. Here and there it is easy to trace the red blood corpuscles, 
 and their part in the production of this congealed substance, by 
 the peculiar color. Also, nuclear detritus and secondary cell heaps 
 are occasionally met with among these patches of congealed sub- 
 stance. 
 
 Beside those diphtheritic portions of the bladder-wall, we find 
 
IO EXPERIMENTAL DIPHTHERIA. 
 
 still large territories occupied by an cedematous hsemorrhagic infil- 
 tration. 
 
 There are now also changes noticeable in the epithelium, of a 
 much greater extent than in previous stages; changes by which we 
 can plainly recognize the transformation of living cells into a diph- 
 theritic and croupous membrane. If one traces out the epithelial 
 layer on one of the sections comprising a very large portion of the 
 affected mucous membrane, and notices as it passes after the more 
 or less affected portions, then he. finds that the epithelial layer, all 
 along its entire extent, has become changed into a homogeneous, 
 uniform, narrow zone or lamella, which still adheres to the mucous 
 layer. The mucosa underlying such lamella is at times infiltrated 
 with cells, and at times, already, no trace of any nuclei can be found; 
 such places, in which both mucous and sub-mucous layers have be- 
 come transformed into a diphtheritic patch, are very convincing of 
 the fact that the upper zone of it must have been produced by the 
 transformation of the original epithelial layer into a homogeneous 
 lamella. 
 
 In figure 4, for instance, that portion of the diphtheritic scab 
 which is situated between the upper bluish-red line on the surface, 
 and that brownish-red stripe below (due to a haemorrhagic infiltra- 
 tion), is transformed epithelium. Of this it is easy to convince one's 
 self, and all that is necessary to do is to trace this line to the margin 
 of the scab, where one will arrive at a point at which this layer will 
 gradually verge into one of still plainly recognizable epithelium. 
 
 In other places we meet in place of the epithelium, sometimes 
 homogeneous, sometimes a more or less firmly reticulated structure 
 heaped up considerably, and exceeding by far the natural thickness 
 of the epithelial layer. In some more fortunate places one finally 
 sees how a still preserved epithelium can be seen passing into a 
 heap of irregularly shaped lumps, whose shape still reminds us of 
 that of epithelial cells, but whose nuclei have ceased to be visible, 
 and closely adjoining it we once more find an amorphous or fibrous 
 substance representative of the membrane. 
 
 In figure 3, we have pictured a croupous membrane occupying 
 the place of the epithelium, and resting upon the mucous layer, 
 which shows a very abundant nuclear infiltration. 
 
 (e) Almost the same description as that just given of the ap- 
 pearances of the mucous membrane of the bladder in the previous 
 
EXPERIMENTAL DIPHTHERIA. II 
 
 stage of disease, would also answer for the appearances presented 
 by the bladder of an animal killed at the end of the fourth or fifth 
 day of the operation, only the coagulation-necrosis becomes the 
 most prominent characteristic, while the haemorrhagic infiltration 
 almost disappears. 
 
 Before pursuing further the process of the disease, it would, 
 perhaps, not be useless to devote a little time to the consideration 
 of the anatomical picture of the disease which has been gradually 
 developed before our eyes. 
 
 Did we have a right to use the word "diphtheritic" in the above 
 description of the condition of things as they presented themselves — 
 have we here really to deal with a disease of the mucous membranes 
 which resembles human diphtheria ? This question can, perhaps, 
 without reserve, be answered in the affirmative, so far as concerns 
 the morphological identity existing between the local process of the 
 disease as it occurs in man, and that which has been experi- 
 mentally called into existence in the bladder of the rabbit. Let us 
 first consider the changes which we have observed in the epithel- 
 ium, and we find on the beginning an cedematous swelling and 
 haemorrhagic infiltration ; then follows, under the development of 
 peculiar changes in shape, which we know from a description of hu- 
 man diphtheria many years since, — the death of the cells, the trans- 
 formation and metamorphosis of very extensive territories of the 
 epithelial stratum — into lifeless masses; and next the new formation 
 of a fibrinous membrane, formed partly from the dead-cell-material, 
 and partly from material furnished by the extravasated blood 
 constituents. This is evidently the same process which underlies 
 the production of the diphtheritic croup of man, and as it has 
 appeared more clearly from the later investigations of Weigert. In 
 the majority of cases of human diphtheria the process is limited to 
 this class of croup. The latter, indeed, as Weigert has ascertained, 
 is anatomically in the throat, larynx and trachea, as a mere superficial 
 coagulation-necrosis, with the products of coagulation super-imposed, 
 not interposed, and is therefore called pseudo-diphtheria.. 
 
 In those experiments of ours, we find, however, more than a 
 mere superficial diphtheria; we find a tissue-diphtheria. The tissues 
 of the entire mucous and sub-mucous membranes have become 
 changed into diphtheritic patches; it dies and swells up on account 
 of its having become infiltrated by a coagulable fluid material. This 
 
12 EXPERIMENTAL DIPHTHERIA. 
 
 death of the tissue by coagulation under an increase in volume, is not 
 generally met with to the same extent and in so many cases as it has 
 been found in our experiments; but it is met with very extensively in 
 human pathology, where we, with perfect right, speak of genuine 
 diphtheria, namely, the diphtheria of scarlet fever and epidemic 
 dysentery. Our experimentally produced diphtheria, indeed, resem- 
 bles much more the processes of the production of the latter two 
 than those of the products of primary human diphtheria. 
 
 This circumstance, however, will be at once understood when it is 
 remembered that we were obliged to put the entire bladder wall and 
 not only the most superficial epithelial layer simultaneously under the 
 same influence and under the same condition; and, therefore, we 
 are still free to believe that an isolated influence of the mucous 
 membrane would also have produced an isolated case of disease and 
 such would be identical with that same disease of the mucous mem- 
 brane which we meet with in primary human diphtheria. That 
 this really does succeed under certain circumstances will be shown 
 later on. 
 
 If this is accepted, it follows that the experiments above de- 
 scribed point to a new and certain method by which the diphtheritic 
 process of mucous membranes can be artificially induced in the 
 animal; this method has the advantage over that hitherto in use, 
 in that the result is produced not by a direct lesion of the diseased 
 mucous surface, but that the disease which is induced is brought on 
 from a distance, and in this respect the method of artificial produc- 
 tion resembles much more the pathological process necessary for the 
 production of diphtheria in the human subject. 
 
 But still it would, after all, not amount to a great deal, if it did 
 not at the same time give us an opportunity of following out the 
 development of the entire process in a much more exact manner 
 than it has hitherto been possible to do, if it did not present us with 
 new features relative to the immediate causation of diphtheria. 
 
 And now, therefore, we must analyze and find out what it is 
 that really happens when we ligate, en masse, an organ provided with 
 a mucous membrane. 
 
 The two most essential results of this ligature around the entire 
 bladder are the following: 
 
 i. The blood in all the arteries, veins and capillaries, in fact, the 
 blood contained in the entire vascular tree of the organ, stagnates 
 
EXPERIMENTAL DIPHTHERIA. 13 
 
 for the period of two hours; or in other words, the velocity of the 
 circulating blood in all the branches of the ligated arteries and 
 veins = o. 
 
 The tension of the tissues need, therefore, not necessarily ex- 
 perience or be subjected to any alteration, because nothing can be 
 admitted and nothing flow off; all movement ceases and the only 
 change which can possibly take place is in the normal processes of 
 diffusion between the contents of the blood-vessels and the fluids 
 outside of them, but even this only takes place to a limited extent, 
 since the chemical composition of the fluids during the two hours 
 the ligature is on, is not essentially changed. Or, shall we accept 
 the interpretation to the effect that, during this time, decomposition 
 takes place, and that the products thereof are diffused through the 
 coats of the blood-vessels and prove hurtful to the tissues? This in- 
 terpretation has been rendered improbable, if not impossible, by an 
 experiment of Cohnheim, who has proven the fact that the same kind 
 of a process of inflammation is produced in any vascular district in 
 which the vessels have for a time been ligated, and the blood having 
 been substituted by salt solution; so that whether stagnated blood or 
 a salt solution fills the vessels, the result of readmitting the normal 
 circulation is the same, and therefore decomposition of the circulating 
 media can have but little to do with it. 
 
 But, and this is the most important thing for the understanding 
 of the entire process, the stagnated blood within the vessels remains 
 in a fluid state; it remains transportable. The column of blood, on 
 removing the ligature, is again moved on, fresh blood re-enters and 
 circulates through the vessels in which before it had been stagnated. 
 If, however, it does happen, as, indeed, it sometimes will, that co- 
 agulation takes place, then a simple tissue necrosis is the result. 
 One of the requirements, therefore, is that the vessels remain 
 open. 
 
 2. The entire mass of tissue of the bladder included in the 
 ligature, and not excepting the coats of the blood-vessels, is deprived 
 of its normal nutrition for the period of two hours. But in a short 
 time, the tissues will commence to absorb oxygen from the blood 
 contained in the capillaries, and give off carbonic acid instead; they 
 may even receive albuminous material from the plasma, by diffusion; 
 but soon everything of that kind must cease, until a renewed afflux 
 of blood takes place. 
 
14 EXPERIMENTAL DIPHTHERIA. 
 
 Whether any abnormal conditions of excitation are caused by 
 any injury, done to ganglion-cells in the process of ligating, such for 
 instance, as contraction or other nervous influence, remains un- 
 known, and may fairly be disregarded for our purpose. 
 
 That very great alteration of tissue, during the time of the 
 ligature being in place, does not take place, can easily be demon- 
 strated by comparing the exterior of the bladder before ligation, 
 with the time when the ligature is about to be removed; no change 
 in appearance can be noticed. 
 
 Let us, then, consider the second head and ask ourselves 
 how far the production of diphtheria is influenced by the direct 
 consequences of the deprivation of the tissues of their normal 
 nutrition for two hours, and we receive a very precise answer, indeed, 
 from our experiments, in studying the behavior of the epithelium 
 after the ligature. Epithelial cells, sooner or later, but inevitably 
 at the end of a certain time, pass through a series of changes which 
 terminate in the death of the cell; and this death must be induced 
 by the lack of nutrition, in fact, inanition brought about by the liga- 
 ture. For the same thing cannot be explained by the processes which 
 are in action after the ligature is removed and the normal circulation 
 has been re-established. The most copious transudations of blood, 
 serum of blood, and lymph corpuscles upon the mucous surface, are 
 entirely unable to bring about death of the epithelia, a fact which is 
 well-illustrated in many cases of catarrhal affections, in broncho- 
 blennorrhceas, in gonorrhoea and the intense hemorrhagic oedemata 
 affecting the conjunctivae and lungs. In all these cases, even if they last 
 many hours, the epithelia of the affected mucous membrane remains, 
 as a general thing, alive. We are, therefore, compelled to look upon 
 the ensuing necrosis as a thing by itself, and as directly produced by 
 the. blood stagnating, and not by the consequent inflammation which 
 ensues on the re-admittance of the normal blood-current. Also 
 Litten looks upon the necrosis and death of renal epithelia as due to 
 arterial anaemia of the organ. Consequently, what is true in the case 
 of epithelia, what we are thus enabled to study step by step on 
 epithelia, must also be true for the rest of the tissues under the 
 same conditions. The cells of the connective tissue corpuscle as well 
 as those of the muscle, showa gradual disappearance of their nuclei 
 and a paling of their normal contour, until a complete dissolution of 
 all and every kind of tissue has taken place. 
 
EXPERIMENTAL DIPHTHERIA. 15 
 
 Even the walls of the vessels undergo an analogous change; all 
 the constituent elements, endothelia and muscular tissues are exposed 
 to the same condition of inanition and suffer the same consequences 
 of that condition. The blood, therefore, which circulates through 
 them after the removal of the ligature will circulate in an abnormal 
 system of vessels, and therewith we have the second element which 
 plays a most important role in the causative production of artificial 
 diphtheria: the so-called inflammatory exudation. 
 
 Cohnheim has already sufficiently established the fact, that the 
 interruption of the normal blood-current produces a lesion in the 
 walls of the blood-vessels, a molecular alteration as it has been 
 called lately, the consequence of which is a greater liability of these 
 walls for letting their contents pass through them. The most super- 
 ficial examination of our experiments shows that these results are 
 thereby confirmed. The large number of minute and large haemor- 
 rhages into the tissues, the marginal position of the white blood- 
 corpuscles in the veins, and finally the enormous oedema which every 
 time make their appearance at the end of the first day, all this 
 proves conclusively, that a change has taken place in the walls 
 of the vessels which tends to produce a copious infiltration into 
 the surrounding tissue, of serum and colloidal material through the 
 coats of the blood-vessels. 
 
 In the interpretation of this peculiar alteration brought about 
 in the vessels, we can now go a step further than Cohnheim. 
 From an analogy with the rest of the tissues we may draw the con- 
 clusion, that this peculiar alteration is nothing else than the com- 
 mencement of the death of the vascular walls, the beginning of a pro- 
 found disturbance in the nutrition which likewise terminates in the 
 death of the vascular walls, or at any rate may do so. For, of course, 
 it must be admitted that, as in the case of the epithelium, the vascu- 
 lar walls may recover from this disturbance of nutrition and return 
 to the normal condition. We may even go further and affirm that 
 the vascular walls offer much more resistance to the disturbance of 
 nutrition than any of the rest of the tissues. Nevertheless, the inherent 
 relation of both these conditions remains, and we may, perhaps, look 
 upon the inflammatory alteration in the vascular walls as the first 
 stage in the process of dying. 
 
 It is of the greatest importance in diphtheria that, for the 
 beginning of the process, the complete death of the walls of the 
 
l6 EXPERIMENTAL DIPHTHERIA. 
 
 blood-vessels is prevented, for in such a vessel the blood would coag- 
 ulate, and that nothing else but a profound alteration in the coats of 
 the vessel is present, into which blood now flows under the normal 
 pressure. With the readmission of blood under normal pressure 
 begins the exudation of the blood constituents, which process forms 
 the second factor in the production of death of the tissues by coag- 
 ulation. 
 
 For if we take into comparative consideration the relation of 
 the exudation to the diphtheria, which is in consequence thereof 
 produced, we see that just in these places, where the disease of the 
 walls of the vessels, with its consequences, is the most prominent, 
 there diphtheria also is most pronounced; that these cedema- 
 tous swellings give rise to diphtheritic patches, yea, that in many 
 places the origin of a cellular hemorrhagic infiltration can be 
 directly traced to coagulation. It results therefrom, naturally, that 
 this second factor is rather the more important in the process of the 
 formation of the diphtheritic patch. But at the same time it is ob- 
 vious that it is conditional, that the complete death of the vascular 
 walls is prevented. For when, this happens — and examples of that 
 kind were very numerous in the course of my experiments on certain 
 parts of the bladder wall — the result is simple unmodified death of 
 tissue, but not coagulation-necrosis, and already at the end of the 
 first day there will be found in these respective places when that has 
 happened, a thin, dry, parchment-like, pale-yellow skin, within which 
 no trace of any swelling can be found. It is certain, then, that the 
 vascular walls must remain alive where diphtheria is expected; but 
 just as important as the remaining alive of these walls, is also the 
 fact that they must not remain normal. For without the inflamma- 
 tory change — this also is well illustrated in some of my specimens — 
 the blood-vessels likewise become distended with blood on removing 
 the ligature; but this will not be sufficient to bring about this 
 copious exudation, which we invariably find in the diphtheritic por- 
 tions. Without disease of the walls of the bloodvessels no swelling 
 of the portions afterwards coagulating would occur, and no diph- 
 theritic patches be produced. On this point I cannot agree with 
 Litten, who believes that the normal transudation of lymph from 
 normal bloodvessels is sufficient to produce coagulation necrosis. 
 His method of experimentation is, however, different from mine, 
 and, therefore, a direct comparison of the results obtained by both 
 
EXPERIMENTAL DIPHTHERIA. I 7 
 
 methods cannot very well be made. His coagulation-necrosis did 
 not attain the extent that mine did. 
 
 Then again, the mere disease of the walls of the blood-vessels 
 is in itself not sufficient to cause coagulation-necrosis or diphtheria. 
 If this were the case it would hardly be intelligible why it could not 
 be produced immediately after the removal of the ligature, or at 
 least in a few hours after a sufficient quantum of blood constituents 
 has made its way out of the vessels into the surrounding tissue. 
 We find, on the contrary, as a rule, that up to the end of the first 
 day, it is wanting, and that during the course of the second day we 
 note the beginning of its development. But it usually makes its 
 appearance when the necrosis of the epithelia, and that of the tissue 
 immediately surrounding the diseased vessels, is complete. We 
 have in the behavior of the epithelia, shown how this death or pro- 
 cess of dying, is gradually brought about, and how, furthermore, 
 soon after death, also coagulation-necrosis appears, and in place of 
 epithelia fibrinous membranes arise. We must imagine the method 
 of production in this manner: the tissues at the moment of their 
 death give off a peculiar fibrino-plastic substance, in order being 
 surrounded and completely permeated with fibrogenic blood plasms, 
 to produce a coagulation material which has a much greater volume 
 than was possessed by the original tissue. This permeation with 
 fluid is caused by that copious inflammatory exudation, and, in the 
 further course, these transuded blood constituents share in the 
 formation of the constantly increasing extent of the coagulation ne- 
 crosis as long as circulation exists. 
 
 So we see it now demonstrated and proven that the definition 
 of diphtheria which was given by Cohnheim is correct, and that it 
 consists in a very intimate relation between inflammation and 
 necrosis. 
 
 It is to Weigert, who took the first step in the right direction, 
 that we owe a correct explanation of the entire process. He discov- 
 ered that it was conditional on the production of a croupous coagula- 
 tion on any mucous surface, that the necrosis of the epithelium had 
 preceded it; that, however, at the same time the mucous and sub- 
 mucous connective tissue remained undestroyed; in other words, 
 that the circulation of the blood in those vessels adjacent to the 
 surface remained intact. But it was not very well explained why it 
 
 was that such a copious transudation of lymph and lymph-corpus- 
 §2 
 
EXPERIMENTAL DIPHTHERIA. 
 
 cles should take place, in order to give rise, under the circumstances, 
 to such fibrinous thickenings. This point has, however, become 
 explicable even in the face of his experiments. For the action of 
 no caustic, whereby epithelium is destroyed throughout its whole, 
 thickness, will necessarily limit its action to the epithelium, but will 
 produce a simultaneous destructive action, at least, to the walls of 
 those vessels of the mucosa which are situated near the surface. It 
 is just in view of this that those volatile caustics, such as ammonia 
 and carbolic acid, produce the best croupous membranes. The fact 
 that a mere tissue-necrosis, the vessels and normal lymph-stream be- 
 ing intact, cannot produce a coagulation-necrosis that is diphtheria, is 
 pretty well established and proven, according to my opinion, by 
 cauterization of the central portion of the cornea. If the centrum 
 of the cornea is carefully cauterized, no change in the remote blood- 
 vessels of the conjunctiva occurs; a circumscribed necrosis of the 
 epithelium is produced, in the neighborhood of which lymph circu- 
 lates undisturbed: but a diphtheritic membrane cannot be produced 
 in this way. 
 
 It must, necessarily, be pre-supposed that in all experiments at 
 the time, when, in consequence of the necessary steps of. the oper- 
 ation, the epithelial tissues had died, the blood vessels, although 
 much altered, were still alive, and circulation of blood within them 
 and transudation of blood constituents from them into neighboring- 
 tissues were still possible. This admits of direct proof. 
 
 During some other experiments which I made for quite a differ- 
 ent purpose, I stumbled upon a method by means of which it is easily 
 possible to produce a very fine self -injection of the blood vessels, and 
 one that only becomes complete and perfected within the last few hours 
 of life. When an animal is inoculated with bacillus anthracis, a cer- 
 tain time always elapses before these bacilli have multiplied and 
 have become developed to such an extent that the entire vascular 
 system has become filled with them. As soon as this has happened, 
 life is, of course, impossible, and death supervenes at the end of a 
 few hours. These bacilli can, by properly staining them, be traced 
 out distinctly, and in thin sections not one need escape the eye of 
 the observer; and thereby we have a means at our hands by which 
 it is easily possible to follow out the course of the blood-vessels, 
 even such as have not a single corpuscle left in them. 
 
 By means of this method, when inoculation and ligating are 
 
EXPERIMENTAL DIPHTHERIA. 1 9 
 
 properly combined, we can show that even in those places which 
 have already become changed into coagulation-necrosis, circulation 
 must have existed even shortly before death, and that, consequently, 
 exudation must have been going on. 
 
 Fig. 4 represents part of such a diphtheritic patch in which 
 blood-vessels are still present, filled with blood and bacilli anthracis 
 which could only have gotten there two hours before death. The 
 only living stainable nuclei of the original tissues are those of the 
 muscles of the smaller arteries and the walls of the veins; they have 
 already d,ied ; nevertheless even in these, circulation had gone on at 
 least a few hours before death occurred. 
 
 Thus it is shown, what has already been mentioned above, that 
 the walls of the bloodvessels exercise more resistance to the 
 destructive influence due the interruption in the normal circulation, 
 than the rest of the tissues, and that their cells will occasionally 
 remain alive even in the midst of the surrounding dead tissue; 
 and the conclusion is justified, namely: that, on the other hand, they 
 are also capable of a much more rapid recovery, restitutio ad integ- 
 rum, more especially in those places in which the surrounding tissue 
 contains material still alive. This is of importance for the under- 
 standing of this croupous affection of the mucous membrane. 
 
 If, then, so far, we have been able to recognize and properly 
 appreciate both conditions which are necessary for the production of 
 diphtheria, it will be comparatively easy for us to explain the varia- 
 tions which have occurred during these experiments. 
 
 First, as already mentioned above, it is intelligible why in all 
 my experiments not croup, or surface diphtheria, but tissue diph- 
 theria (Weigert's true diphtheria) was produced. We have to 
 deal with a diseased condition of the entire bladder wall and its con- 
 stituents, consequently diphtheritic deposits must occur in all the 
 different layers. It only rarely occurs that the fundus of the 
 bladder which has been ligatured off is uniformly affected, some 
 places being always more affected than others. The same was 
 found by Cohnheim in his experiments. This may depend upon, 
 perhaps, two things : First, the ligature may not in all cases be 
 equally tight, or may not affect one portion as much as another and 
 only retards the circulation in some parts, while in others it 
 may entirely arrest it ; second, it may also depend upon the indi- 
 vidual resistance of some animals, as well as that of some tissues. It is 
 
20 EXPERIMENTAL DIPHTHERIA. 
 
 easily to be imagined that certain portions of the bladder might be 
 more readily affected than others by the same operation; that in the 
 one the damage done is beyond recovery, in the other it is not, or 
 that also a portion of the bladder having previously been under 
 a more favorable condition of nourishment will be longer in dying 
 than others. And inasmuch as these differences are again subject 
 to two different factors, the transudation from the vessels of one and 
 the disturbance in nutrition on the other hand, which factors are 
 not congruent in time, it is to be expected, a priori, that a diphtheritic 
 bladder may look very different in different animals. In some instances 
 these diphtheritic patches are found situated in or near the groove 
 of the ligature; in others remote from it in the fundus of the bladder; 
 again in others we find a coherent territory; and in still others we come 
 across small patches scattered through the hemorrhagic cedematous 
 mucous membrane. Sometimes these patches are developed more 
 prominently in the mucous and sub-mucous layers, more rarely so in 
 the muscular and serous layers ; in some cases diphtheritic patches 
 are developed quickly and abundantly; in others they are scarce and 
 develop slowly. As a general thing, however, their number and 
 extent increase in accordance with the time which elapses between 
 the removal of the ligature and the examination. At any rate, it is 
 of interest, and deserves to be accentuated, that every time after one 
 operation and treatment of the animal, we obtained that peculiar 
 diseased condition of the mucous membrane which is constantly 
 met with in human diphtheria. 
 
 If we imagine a case in which the causes of this diseased 
 condition lie principally in the superficial strata and could only 
 exert their destructive influence upon the epithelium covering the 
 surface of the mucous membrane, while the rest of the tissues did 
 resist, we should certainly have a genuine croup or a surface diph- 
 theria. 
 
 A fortunate accident has given me an example of it: (Experi- 
 ment VII.) On the afternoon of the 23d of March, i88i the 
 bladder of a certain sick rabbit was ligated. On the 26th it was 
 inoculated with bacillus anthracis. It died on the 29th, at 1:00 p.m., 
 in other words, at the end of the sixth day. Here I found the blad- 
 der externally very well preserved, the internal surface, however, 
 throughout its whole extent showed the most beautiful croupous 
 appearances. Fig. 3 is taken from a section through the most 
 
EXPERIMENTAL DIPHTHERIA. 21 
 
 superficial croupous layer of the mucous surface. One recognizes 
 the enormous thickness of the croupous stratum and also the 
 adjoining; the most superficial layer is already undergoing coagula- 
 tion-necrosis with nuclear detritus. 
 
 If we now scrutinize these experimental results and look upon 
 them in the light of human pathology, the conclusion is justifiable 
 and almost unavoidable, that there is a strong possibility, which 
 cannot be disputed, that diphtheria may originate in the human 
 subject in exactly the same manner as has been shown in my ex- 
 periments; that, in other words, it must be admitted that a non- 
 infective diphtheritic affection of the mucous membrane may exist. 
 To experiments by means of cauterization, it might have been 
 objected, that those conditions did not answer to those which pro- 
 duced diphtheria in the humansubject. The development and pres- 
 ence of such mechanical conditions, however, as I have artificially 
 induced to produce diphtheria, are, indeed, easily imaginable in the 
 human subject. Let us suppose, for instance, a spasm of a number 
 of small arterioles near the mucous surface (say, perhaps, reflexly 
 by the action of cold on the mucous surface or the general surface) 
 lasting for the period of two hours, which is sufficient to produce an 
 arrest of the circulation in at least the remotest capillaries, that is, 
 those situated nearest the surface; supposethis condition of things 
 should be followed by a reestablishment of the circulation, and it 
 cannot fail that in such cases at the end of one and a half to two 
 days, without the aid of a single micrococcus a croupous exudation 
 is produced. That such a spasm of the blood-vessels might, 
 under certain circumstances, continue to last two hours and lead 
 to a complete arrest of the circulation, remains to be experiment- 
 ally proven; in the meantime this is still conceivable. 
 
 Or, in case that a rheumatic affection and swelling be developed 
 along the branches of the connective tissue capsule of the tonsil, 
 through which the blood-vessels take their course, and would give 
 rise to compression of a number of arterioles and capillaries lasting 
 for several hours, which again must have a temporary stagnation in 
 the circulation for its consequence, we again would have a tonsillar 
 croup produced in a mere mechanical way. 
 
 In the same way it is possible that, e.g., a spasm in the large 
 intestine, enclosing a very thick ball of fcecal matter, may by press- 
 ure upon the epithelial-cells produce their death and at the same 
 
22 EXPERIMENTAL DIPHTHERIA. 
 
 time cause disease of the superficially located blood-vessels from 
 compression — and here again the two conditions are given for the 
 production of exudation with coagulation. In quite a similar man- 
 ner, under certain circumstances, the pressure produced by a gall 
 stone upon the mucous surface of the contracted gall ducts, etc., 
 might produce similar results. 
 
 In short, the causation of croupous or diphtheritic disease of 
 mucous membranes in the human subject, through mechanical inter- 
 ferences, is explained by the above experiments, and its independent 
 occurrence rendered probable. It is just this which is of so much 
 importance in (clinical) croup and (clinical) diphtheria. Those who, a 
 priori, deny the possibility or probability of a genuine croup being 
 produced without a diphtheritic poison, are welcome to dispose of 
 the above facts. 
 
 Finally, we must direct attention to the fact, that the form and 
 site of the coagulation-necrosis depend not essentially on any inequal- 
 ity, in the causes underlying them, but simply on the place whereon 
 they may find a suitable point of attack. The process of the produc- 
 tion of Weigert's pseudo-diphtheria, or croup, is, then, essentially 
 the same as that of genuine tissue diphtheria, which latter is beauti- 
 fully illustrated and developed in scarlatina, and differs from it in 
 only this respect, that in the latter only the epithelium and superficial 
 capillaries are affected, while in the former, both mucous and sub- 
 mucous layers, including the blood-vessels, are implicated in the pro- 
 duction of coagulation-necrosis. 
 
 There is, however, one very important circumstance, which 
 seems to distinguish the two pathological processes as going on in 
 man in croup and diphtheria, one from the other; it is just this which, 
 especially with respect to the therapeutics of the pseudo-diphtheritic 
 diseases of the larynx and trachea, plays such an important role- 
 This is the well-known fact that in man, after the croupous mem- 
 brane has been thrown off, a new one is formed in the same place, 
 while in genuine diphtheria, loss of substance and ulcer will be the 
 result. 
 
 How is this to be explained? Let us look once more at the con- 
 ditons which are necessary to the production of a croupous mem- 
 brane. From what has been said before, they will have to be looked 
 for, first, in the process of dying, with coagulation of the epithelium 
 of the trachea; second, in a diseased condition of the most superficially 
 
EXPERIMENTAL DIPHTHERIA. 23 
 
 situated capillaries of the mucous tissue. Mark well the difference 
 in a disease of the capillaries and veins not resulting in immediate 
 death. This is the point of so much importance. For, what hap- 
 pens when a croupous membrane is thrown off ? As is well known, we 
 find just before the membrane is thrown off, between the latter 
 and the surface underneath it, a layer or two of cells, commonly 
 called pus. The mucous layer then, after throwing off its epithelial 
 layer, lies still exposed with its still diseased capillaries covered 
 only by several layers of lymph cells, as it was formerly covered 
 by epithelium. If these causative conditions, which brought about 
 the death, of epithelial layers and the disease of the capillaries, con- 
 tinue to exist, it would be just what could be expected to see a new 
 and abundant transudation of fibrinogenous substance produced, and 
 the fibrinoplastic substance- is contained in the dying, superficially, 
 located cells. The explanation for these recurrences of new mem- 
 brane is found in the fact that the blood-vessels continue in their 
 diseased condition. As soon as they recover and become again nor • 
 mal, the new formation of croupous membrane will cease. The 
 fact, however, that the walls of the blood-vessels will much easier 
 and more quickly recover and return to their normal condition than 
 the rest of the tissues, has already been sufficiently dwelt upon 
 above. 
 
 It is a very different thing with the genuine tissue diphtheria. 
 Here the diseased blood-vessels are completely surrounded by dead 
 tissue, and here the death of tissue will eventually also extend to the 
 enclosed blood-vessels, which is not the case in croup. 
 
 We have seen that the circulation will continue for a time in 
 those blood vessels which are in the midst of coagulated tissues; 
 that, in other words, death of tissue precedes that of the vessels, 
 but eventually death of the vessels takes place, and no recovery is 
 possible. So far, then, as tissue diphtheria extends, everything — cells, 
 intercellular substance, vessels — all must die. After the throwing off 
 of the mass of dead tissue an ulcer remains. And now it is intelli- 
 gible why here, unlike what happens in croup, no new exudation 
 takes place. For only so far as the loss of substance reaches, was 
 the characteristic disease of the vessels and tissues present; beyond 
 it the causative conditions have been imperative, and no coagula- 
 tion-necrosis, consequently, has been the result. In such cases we 
 only get simple re-active inflammation, but no diphtheria. 
 
24 EXPERIMENTAL DIPHTHERIA. 
 
 By means of the experimental study just described, we have 
 been enabled to split up the local process of diphtheria into its com- 
 ponent parts — into its immediate causative elements. And now we 
 are justified in accepting the fact that these immediate causative 
 conditions underlying the production of this peculiar disease of the 
 mucous membrane, are the same in the disease affecting the human 
 subject ; a very profound interference in the nutrition of certain 
 tissues, mostly the epithelium and, not very rarely, in the most super- 
 ficially situated blood-vessels, in the mucous and sub-mucous layers, 
 etc. And inasmuch as in human diphtheria we have to deal with a 
 disease poison as the primary cause of all the accompanying disease- 
 processes, we are, furthermore, justified in concluding that this par- 
 ticular poison is also the ultimate cause of that interference in 
 the nutrition of the epithelia, mucous membrane, blood vessels, etc. 
 In what manner, however, this poison gives rise to this local diph- 
 theria, these changes so unfavorable to the maintenance of the 
 normal conditions in the epithelium and other tissues, is another 
 matter, and not shown by our experiments. It is evident, a priori, 
 that this can be done just as well by a direct action of the poison on 
 the cells from without, or through the blood vessels, as also indi- 
 rectly, e. g. y by an irritation of the vaso-motors of the parts, or in 
 some such way. 
 
 From my experiments it has been rendered certain that the 
 local condition, or disease of the mucous membrane, stands in no 
 sort of causative relation to the general processes observed in human 
 diphtheria. 
 
 For this it will only be necessary to look back upon the general 
 condition of these animals operated on, and it will be seen that in 
 all aseptic cases this has in no case been at all affected. The ani- 
 mals all behaved just as was described in the first experiment. 
 There is no lack of appetite, no fever, the behavior of the animal 
 remains the same; in fact, this experimentally-produced diphtheria 
 is a local affection, and remains such throughout. This process can 
 be followed out for several days, inasmuch as the local process here, 
 unlike what happens in croupous affection of the trachea, does not 
 produce death mechanically. If, then, we follow out this process 
 somewhat further, we find the following: First, it becomes neces- 
 sary now to mention what has heretofore been left unnoticed, and 
 that is this: It sometimes happens more especially in those dead 
 
EXPERIMENTAL DIPHTHERIA. 25 
 
 portions of the diseased bladder which may either be simply necro- 
 tic or diphtheritic, that we find accumulations of bacteria, occurring 
 sometimes in irregular figures within the necrosed tissues, some- 
 times in long, densely aggregated platoons. These bacteria con- 
 sist in simple bacilli, 1.5-1.8 jd. long, and one-third as broad, corre- 
 sponding, therefore, to the ordinary bacterium dermo; they are well 
 stained in alkaline aniline colors.. Be it now, that these germs get 
 into the bladder during the operation, or be it that they were origi- 
 nally contained in the blood, they were, by no means, able to main- 
 tain their vitality in the living tissue, but only found a fertile soil in 
 the dead tissue. For such accumulations are not found anywhere, 
 where the tissues still show staining of the nuclei ; nor are they to 
 be found within the croupous membranes, but only and exclusively 
 in the dead tissues of the bladder wall, and in this way they serve as 
 an indication as to the extent of the tissue-necrosis. They do 
 not, therefore, possess the significance of pathogenic micro- 
 organisms. 
 
 The dead tissue, however, does not remain very long in statu 
 quo. A molecular detritus is produced therefrom and in conse- 
 quence thereof a loss of substance results, which in those places, 
 where the disease has attacked the whole thickness of the walls, pro- 
 duces holes in the organ. Perforations of that kind I have observed 
 sometimes on the sixth day, always on the tenth and twelfth day of 
 the disease, and in animals which, up to the time when they were 
 killed, had been entirely well and had even successfully withstood 
 other operations as, for instance, that of transfusion. The reason 
 why such bladder perforations have so little influence is that, 
 simultaneously with the advancing death of those portions of the 
 fundus of the bladder, a new formation of connective tissue takes 
 place around them, whereby the bladder is cemented on to the 
 abdominal wall, or loops of intestines or uterus, as the case may be. 
 Eventually a shrinkage in toto of the entire bladder ensues; on 
 some places we find the remnant of the dead tissue, like yellowish 
 little heaps over the still healthy portions of the serous layers of 
 the bladder, and the final result of the entire process is, that the 
 animal is minus the fundus of its former bladder and instead of 
 that possesses a connective tissue-cicatrix; otherwise, however, no 
 damage has been done to the general health. 
 
 In order, however, to obtain still further proof of the harmless- 
 
26 EXPERIMENTAL DIPHTHERIA. 
 
 ness of the diphtheritic disease, several inoculation experiments 
 were undertaken with these artificially produced diphtheritic 
 patches. 
 
 Experiment XX. — On the 24th of September, 1881, we 
 operated in the usual way on a medium-sized, black rabbit. Four 
 days later it was killed, while in apparently perfect health. The 
 portion of the bladder which had been ligated is found partly in a 
 condition of a high degree of hemorrhagic oedema, partly covered 
 with a yellowish streak, by its color, well differentiated from the sur- 
 rounding swollen-up parts. 
 
 The bladder is distended, carefully cleaned, and a few pieces of 
 the diphtheritic patch cut off with scissors and rubbed into wounds 
 made for the purpose of inoculation at the root of the tails of several 
 white mice. Another piece was taken and placed under the skin of 
 a rabbit and kept there by sutures. 
 
 The mice experienced no disturbance, and were living and get- 
 ting along well during the first week in October. 
 
 The rabbit on October 19th is getting along well, eats well, etc. 
 At the place operated on an abscess was formed which was found on 
 October 23d, when the animal was killed, to have become thoroughly 
 encysted. The pus obtained from it on October 19th contained 
 some globular and biscuit-shaped bodies ; a mouse inoculated with 
 it remained uninfluenced by it. 
 
 And herewith it was also to be regarded as innocuous to other 
 animals, or at any rate to a very moderate degree. 
 
 We have, then, by reason of this course of experimentation, an 
 analysis of the causes necessary to the production of Breton- 
 neau's membrane, but Bretonneau's disease was not, however, 
 constructed. 
 
 Perhaps (such was the course of thought), the disease might be 
 produced per synthesis, by inducing the characteristic diphtheritic 
 membrane in the usual manner and at the same time adding the 
 diphtheritic poison by inoculation. This was the object of the second 
 part of the experiment. 
 
II. Attempt at an Artificial Combination of 
 Local Diphtheria with General Infection. 
 
 Before attempting a combination of local diphtheria with a 
 diphtheritic general infection, it seems necessary to me, in the in- 
 terest of a clear insight into the process which would probably be 
 developed in an animal with both the local and general disease, to 
 first make use of some inoculation material, the properties of which 
 are exactly known, and the carriers of which will prevent any chance 
 of their being mistaken for anything else, rather than to use at once 
 the micrococci of diphtheria, which are still somewhat surrounded 
 with a certain mystery. For this reason I chose the poison of an- 
 thrax, the bacillus anthracis, for the induction of the general affec- 
 tion. It is well-known that this poison produces in the rabbit a 
 distinctive acute general affection. 
 
 These experiments had, of course, to be so arranged that both 
 local diphtheria and general infection should operate combinedly 
 upon the bladder — that the latter, more especially, did not begin to 
 operate after the local process had already reached completion. This 
 is exactly what afterwards happened in the beginning, and only after 
 many repeated experiments did we find that it was necessary to make 
 the inoculation somewhat early, in order to obtain a simultaneous ac- 
 tion of both ligature and poison. It is, however, well-known, that the 
 duration of life in the rabbit after the inoculation with bacillus 
 anthracis is but short, and that, consequently, only the early stages of 
 diphtheria could be successfully studied, in combination with the 
 infection. It was just this combination which gave us very beau- 
 tiful results. 
 
 The following experiment teaches us how the infection material 
 behaves in the first stages of diphtheria: 
 
 Experiment XXXI. — On November 12th, 1881, between 2:00 
 and 4:00 p. m., a strong rabbit was operated upon in the usual way. 
 Immediately afterwards a fresh crop of bacilli anthracis was inocu- 
 lated into both ears. On the 12th, in the evening, the animal was 
 still alive, but on the morning of the 13th it was found dead. 
 
28 EXPERIMENTAL DIPHTHERIA. 
 
 The fundus of the bladder showed a high degree of oedema, the 
 oedema, however, flowing off rapidly from the sub-mucous spaces. 
 Only in the immediate neighborhood of the furrow of the ligature, 
 four or five little swellings, of the size of a pin's head, were discerned, 
 which, after the collapse of the surrounding mucous membrane, 
 stood out in relief as diphtheritic patches. 
 
 The histological examination showed the beginning epithelial 
 necrosis, hemorrhagic oedema, etc. On those patches was found well 
 pronounced coagulation-necrosis Of the tissues. 
 
 The vessels of the entire wall of the bladder were filled with 
 bacilli anthracis. While the aggregation of bacilli in the larger 
 veins and very wide capillaries only occupied a part of the cross 
 section of their lumen, the majority of the capillaries are entirely 
 filled and crowded with bacilli, so that in the course of such bacilli 
 which had been stained in gentian blue a number of vessels became 
 visible. Those capillaries which are situated immediately under- 
 neath the epithelial layer were particularly crowded with bacilli. In 
 some places it even looked as if these bacilli had penetrated through 
 the capillary walls and made their way into the epithelial layers. By 
 the use of high magnifying powers we succeeded, however, in show- 
 ing that in most of such cases we had to do with oblique sections, in 
 which the epithelial layer happened to lie either above or below the 
 mucous layer, in whose most superficial vascular loops a few stray 
 bacilli were found. Pictures of undoubted proof of bacilli within 
 the loosened epithelia, as was the case with red blood-corpuscles, I 
 have been unable to obtain. Also in the rest of the tissues no bacilli 
 were discovered outside the blood-vessels. 
 
 Fine sections of these rigid little swellings showed a homogen- 
 eous tissue free from nuclei and richly infiltrated with red blood 
 corpuscles. Within such structureless masses could be seen coursing 
 somewhat brighter channels within which were found bacilli, though 
 not so densely crowded together. A closer examination of the 
 boundary of channels revealed feebly stained nuclei at just about 
 the same distance from one another as were the nuclei in the capil- 
 laries and the smallest veins. 
 
 The finished coagulation-necrosis is, then, still permeated by 
 blood-vessels, and by means of these, the diphtheritic patch was still 
 traversed by bacilli, although no extravasation of them had taken 
 place. 
 
EXPERIMENTAL DIPHTHERIA. 29 
 
 The following experiment will show that the bacilli contained 
 within these diphtheritic patches, still possessed the property of an 
 infective poison: 
 
 After the bladder had been taken from the animal and been ex- 
 tended, it was first of all thoroughly cleansed with water, in order to 
 remove any trace of blood which might possibly adhere to it. The 
 mucous surface was then thoroughly rinsed off with absolute al- 
 cohol. One of the segments of the little haemorrhagic swellings 
 was now removed by means of a pair of well-cleaned scissors, and with 
 the juice .pressed out from the cut surface a mouse was inoculated at 
 the root of its tail. At the end of twenty-two hours the mouse died 
 of anthrax. 
 
 This experiment shows that an infectious poison accumulates 
 and, possibly, increases in virulence, in the portions of the mucous 
 surface affected with diphtheria, most of the capillaries being so 
 crowded with bacilli, as is only likely to be the case in simple cases 
 of inoculation. It shows further that the poison can be found in the 
 diphtheritic patches when, at the time of the full development of the 
 infective process, circulation is still going on within the coagulating 
 tissue. The diphtheritic patch has then become poisonous and can be 
 used for the transmission of the infectious disease from one individ- 
 ual to another. We did not succeed, however, in obtaining proof, 
 at least so far as the bacillus anthracis is concerned, that the ba- 
 cilli leave their inflamed blood-vessels, and thus penetrate into the 
 more superficial strata of the diphtheritic membrane. 
 
 Even in a somewhat later inoculation the poison still finds its 
 way into the patch, as is seen from the following experiment: 
 
 Experiment XVIII. — On the afternoon of September 15, 1881, 
 a strong rabbit was operated upon in the usual manner. On the 16th, 
 at 4 p. m., it was inoculated with bacillus anthracis. It died during 
 the night of the 18th, or two and one-half days after the inoculation, 
 and three and one-half days after the diphtheritic infection. 
 
 The diphtheria in this case was much more extensive, but had 
 not developed in a very marked degree. (It had been ligated 
 with rubber tubing.) Very fine diphtheritic patches were found at a 
 short distance from the furrow of the ligature. Within the substance 
 of these patches, a tissue absolutely free from any nuclei, we find 
 some very small, stained bacilli anthracis arranged in rows. Closer 
 observation reveals the fact that they occupied the place of a former 
 
30 EXPERIMENTAL DIPHTHERIA. 
 
 capillary (still to be recognized by its contour), which, before death 
 ensued, had become resolved in the general coagulation-necrosis. 
 The bacilli had remained alive even here in the midst of dead tissue 
 — but, of course, death of tissue had taken place very shortly before 
 the animal itself had died, and, perhaps, very slow and sluggish 
 circulation must have still existed in this situation at the end of the 
 3d day of the disease. On the dead body, however, this place could, 
 with great certainty, be pronounced an anthraco-diphtheritic patch. 
 
 Fig. 4, taken from an analogous experiment, beautifully repre- 
 sents these conditions. 
 
 At a still later inoculation, coagulation-necrosis cannot be com- 
 pletely established before the infectious material could reach those 
 places, and the superficial and submucous patch had no poisonous 
 properties in such cases. 
 
 Experiment XIX. — On September 15th, in the afternoon, 
 another rabbit was operated after the usual manner. On the 17th, in 
 the forenoon, and, for the second time on the 18th (successfully 
 then only perhaps on the third day of the diphtheritic disease), it 
 was inoculated with bacillus anthracis. It died on the twentieth (or 
 on the fifth day of the diphtheria), doubtless of anthrax. In the 
 bladder was discovered a well-defined coagulation necrosis. Inoc- 
 ulation at the root of the tail of a mouse with a portion from the 
 surface of this diphtheritic patch gave no positive result. The 
 mouse died eight days later, but not of anthrax. 
 
 In Experiment VII, above mentioned, when a very beautiful 
 croupous membrane was obtained, the animal had been inoculated 
 at the beginning of the fourth day, and died on the sixth; all 
 perforating vessels were found to be full of bacilli, but neither in 
 the croupous membrane nor in the upper layers of the mucous mem- 
 brane itself, was it possible, in spite of the most careful search, to 
 find any. 
 
 The synthetic experiments hitherto described have demonstrated 
 the fact, that a diphtheric mucous membrane may take up, and 
 store up in considerable quantity, an infectious poison, pro- 
 vided the latter is introduced into the circulation during the forma- 
 tion of the diphtheritic patch when the blood-vessels are still pervi- 
 ous; for it seems impossible, — for the bacillus anthracis, at least — to 
 penetrate the diseased walls of the blood-vessels of the mucous 
 membrane. 
 
EXPERIMENTAL DIPHTHERIA. 31 
 
 After having ascertained these conditions, experiments with 
 the micrococci diphtheriae, which are much harder to diagnose 
 morphologically, were begun: 
 
 Experiment XXIX. — On October 27th, at 3 p.m., a very strong- 
 rabbit was operated on in the usual way ; at 5 p.m. the ligature was 
 removed. During the interval, a small quantity of a diphtheritic 
 patch taken from the tonsil of a nine-year-old boy suffering with the 
 disease (and who succumbed to it on the 2d of November) was intro- 
 duced underneath the long fascia of the back of the rabbit ; the 
 wound was carefully closed. 
 
 On the 28th in the afternoon the animal had a temperature of 
 41.0. C. On the 29th, 38.4 C; on the 30th at noon, 32.5 C. in the 
 rectum. The animal looks unkempt, moves its head spasmodically 
 to and fro; fore paws trembling. At 2 p. m. it died. The body was 
 kept on ice. 
 
 The autopsy was made at 10 a.m., October 31st. The inocu- 
 lated muscle presented a haemorrhagic appearance and was partly 
 pale red, of a colloid lustre. The whole of the sub-cutaneous con- 
 nective tissue of the inoculated side extending from the back to the 
 abdominal wall, was cedematous. Spleen 5 1-2 c. m. long, thickened, 
 dense, partly dark blue, partly brownish-red. Intestines to a 
 large extent empty, without being particularly injected. Trachea, 
 lungs and liver normal. Cortical portion of the kidney hyperaemic. 
 
 The fundus of the bladder shows a certain number of yellow,firm- 
 ly-adhering patches, the mucous surface between these being hsemor- 
 rhagically swollen, and partially traversed by a whitish infiltration ; 
 when placed in alcohol, the epithelium comes off in the shape of 
 a very thin skin — post mortem maceration of those portions of the 
 epithelium which have remained intact. 
 
 According to the results arrived at from this experiment, it was, 
 without doubt, especially well demonstrated by the swelling of the 
 spleen, that by the subcutaneous injection of a certain quantity of 
 a diphtheritic mass an acute infectious disease had been developed, 
 which in a few days caused the death of the animal. 
 
 In order, now, to further ascertain the exact relation of the 
 inoculated poison to the mechanically produced diphtheria, whether 
 here also, the diphtheritic patch had poisonous properties as was 
 the case in the diphtheritic infection produced by the poison of 
 anthrax, a new experiment was at once instituted. 
 
32 EXPERIMENTAL DIPHTHERIA. 
 
 Experiment XXX. — Before putting the Madder of the animal 
 (experiment 29) into alcohol, a very small bit of diphtheritic patch 
 was taken from it, and placed underneath the skin of the back of a 
 rabbit at 10:30 a. m., October 31st. On the afternoon of November 
 2d, at 2:30 p. m. (fifty-two hours after the infection, the first animal 
 being seventy hours after the inoculation), the animal is moribund. 
 Temperature, 366 . 
 
 The autopsy was made at 3 p. m., immediately after death. 
 
 The inoculated muscular fascia shows numerous haemorrhages. 
 The long back muscle shows haemorrhages at the place of inocula- 
 tion, and extending upwards as well as downwards from it, of a 
 peculiar pale color and homogeneous appearance. Trachea free. 
 Lungs pale red. Numerous pleuritic haemorrhages near the margin 
 ofboth upper and lower lobes. Intestines empty; jejunum filled with 
 vitreous slime; nothing abnormal about the lower part of the ileum. 
 Spleen, six centimetres long, one-half centimetre thick, very firm 
 and dark brown. Cortical substance of kidney darkish red, with 
 haemorrhages. Medullary substance paler. Mucous membrane of 
 bladder normal. Several small masses from this (not diphtheritic) 
 mucous membrane were removed. At 4:30 p. m. two mice were in- 
 oculated with them. Both animals remain well. 
 
 The diphtheritic patch removed from the bladder of the animal 
 which was first inoculated had, indeed, very energetic poisonous 
 properties, when the effect of inoculation of a small particle of the 
 same is compared with that of matter coming from a patch of merely 
 local diphtheria. While there only a small abscess was formed around 
 the diphtheritic eschar, we find that here a very acute infectious dis- 
 ease was developed, which produced death quicker than was the 
 case in the primary infection. But that again is due to the fact that 
 prior to the inoculation a diphtheritic local inflammation was pro- 
 duced in the bladder. For inoculations with parts of the healthy 
 bladder of the second animal remained without result. That, how- 
 ever, the infectious poison was contained in the blood of the second 
 animal, we will see presently. For now the qestion arises, whether 
 it can be proven that there was present in the diphtheritic bladder 
 an infectious material capable of augmentation. 
 
 Fine sections from the bladder of the animal from experiment 
 29, where a successful inoculation had taken place; show the fol- 
 lowing: 
 
EXPERIMENTAL DIPHTHERIA. 33 
 
 The diphtheritic process has reached a very considerable extent, 
 so that we find on the one hand the mucous and sub-mucous layers, 
 and on the other the serous and neighboring portions of muscular 
 layers invaded by the coagulation-necrosis, and the layers between 
 these are the only ones which show still distinct blood vessels and 
 other living tissue rich in nuclei. But here we find the capillaries 
 and veins everywhere in a dilated condition. Within these dilated 
 vessels we find rather densely crowded bacilli, very distinctly stained 
 with gentiana blue, and about 0.5 jj. broad and 1 pi long. They 
 are all of a uniform size; they are partly aggregated together in 
 chains of two or four, partly irregularly scattered about through the 
 lumen of the vessel. 
 
 In many places we see, just as in inoculations with anthrax, the 
 bacilli penetrate into the diphtheritic patch by way of the stil) 
 pervious blood vessels. Outside these channels, of course, we fine 
 an abundance of small granules and debris of irregular shape, but 
 the presence of the characteristic micro-organisms cannot be demon- 
 strated. In portions of the bladder wall, which are not diphtheritic- 
 ally affected, but in which the disease is simply inflammatory, we 
 come across very rich aggregations of these bacilli which have pene- 
 trated into the finest mucous capillaries running along underneath 
 the epithelial layer, just in the same manner as we have already seen 
 in inoculation with anthrax. 
 
 Figure 5 represents fragments of two such capillaries running 
 close underneath the swollen and cedematous epithelium, as they 
 appear in diffused light, and shows how very much crowded they 
 are with these micro-organisms. 
 
 These same bacilli can be found in the vascular loop forming 
 the glomeruli of the kidneys, but not in such large numbers as 
 is the case in the diphtheritic bladder of the animal from experi- 
 ment 29. 
 
 These very same micrococci are furthermore found in the loops 
 of the glomeruli of the kidneys of the second animal (Exp. 30), 
 and here they occur partly in the shape of dense colonies, com- 
 pletely filling the capillaries, and forming emboli partly in small scat- 
 tered heaps. 
 
 The emboli of bacteria must have formed in the kidney during 
 life, inasmuch as this animal was dissected immediately after 
 
 death and its kidneys placed in absolute alcohol; and now we may 
 
 §3 
 
34 EXPERIMENTAL DIPHTHERIA. 
 
 be certain that both in the first as well as in the second animal, 
 these very bacilli were the carriers of the infectious material. 
 
 It is, then, certain that the transportation of a certain quantity of 
 diphtheritic patch from the throat of a diphtheritic child, and subse- 
 quent inoculation underneath the skin of a rabbit, produces in the 
 latter animal an acute infectious disease which is characterized by en- 
 largement of the spleen, and by the presence of very small bacilli in 
 the blood, and which disease is furthermore transmissible from one 
 animal to another. This transmissible poison, however, is especially 
 abundant, and stored up richly and perhaps also in a purer state, in 
 the diphtheritically diseased mucous membrane of the animal than it 
 was originally. For inoculation with material from the diphtheritic 
 bladder produces death more rapidly than was the case in the first 
 animal, while inoculation of the healthy bladder of the second ani- 
 mal produced no result. 
 
 We have here, then, an analogous condition of things to those 
 which we have observed in the experiments with anthrax, the o|nly 
 difference being that here another poison plays the role which bacil- 
 lus anthracis played in the other experiment. 
 
 A further series of experiments was instituted, using the slimy 
 excretions from the throat of a child sick with scarlatinous diph- 
 theria. 
 
 Experiment XXIV — On the afternoon of October 19, 1881, a 
 medium-sized rabbit was operated on in the usual manner. On the 
 forenoon of the 20th, a small quantity of a slimy mass was scraped off 
 from the surface of the palate and tongue of a two-years-old child 
 suffering with a very acute attack of diphtheritic scarlatina. This 
 slimy mass was kept on a hollow ground slide, carefully covered up 
 under a cover glass until three o'clock in the afternoon of the same day, 
 when it was transported under the skin of the back of the rabbit on 
 its right side. It was the eighth day of the disease, and on the ninth 
 the little girl died. The scraped-off mass consisted o£ mucus, 
 pus corpuscles, epithelia, and detritus, and contained the following 
 forms of bacteria: 
 
 1. Short bacilli and diplococci, movable. 
 
 2. Bacilli in the zooglcea form, immovable. 
 
 3. Longer bacilli very thin (bac. subtilis), movable. 
 
 4. Medium sized micrococci, forming heaps with irregularly 
 defined outlines. 
 
EXPERIMENTAL DIPHTHERIA. 35 
 
 5. Small globular micrococci in densely aggregated heaps in 
 zooglcea form; these heaps have all a brownish color, a pretty regu 
 larly round contour and sharply-marked appearance. 
 
 On October 2 2d, in the afternoon, while taking the temperature 
 of the animal, an abnormally pasty consistence of the faeces was 
 noticed. Otherwise nothing particularly striking was noticed about 
 the animal. On the 23d it was found dead (between fifty and sixty 
 hours after inoculation). 
 
 The autopsy was made on the forenoon of the same day. At 
 the place of inoculation was found a small abscess of the size of a 
 bean, large, purulent infiltrations of the subcutaneous connective 
 tissue, lungs contained air throughout, in a few places small whitish 
 infiltrations in the immediate neighborhood of the blood-vessels were 
 seen, and also in some places in the liver, which was considerably 
 enlarged. 
 
 No trace of peritonitis, nor was there a trace of pus or cheesy 
 material to be found around the bladder. Spleen seven and one- 
 half c. m. long, extremely distended, of a dark red color, capsule 
 strongly distended, parenchyma on the cut surface hard, very pulpy. 
 The large intestine was full of pasty faecal matter. The fundus of 
 the bladder resembled, viewed externally, a very dark-red, globular 
 body, studded here and there with whitish spots. The left ureter 
 (ligated) was much distended, of a reddish color, as was also the 
 pelvis of kidney. Kidney swollen and dark red. Right kidney 
 pale, of normal size; cortical portion hyperaemic and haemorrhagic 
 in places. In the bladder slightly turbid urine. 
 
 Mucous membranes and entire wall of fundus of bladder 
 swollen and strongly hyperaemic and haemorrhagic. Over the dark 
 red and velvety mucous surface, scattered in large numbers, we find 
 yellowish and dark-red patches, firmly connected with the under- 
 lying tissues but reaching out above the level of the surroundings; 
 besides these there are also a few whitish scales. 
 
 Four mice are immediately inoculated with the splenic pulp, 
 another mouse with the blood, and still another with the pus which 
 was found at the place of inoculation. 
 
 The animals inoculated with spleen and blood died on the 
 third day; those inoculated with the pus, on the fourth. Be- 
 sides (exp. 25) on Oct. 23rd, at 12:30 p. m., a small portion from a 
 diphtheritic patch from the bladder was brought underneath the 
 
7,6 EXPERIMENTAL DIPHTHERIA. 
 
 skin of the back of another rabbit, in which forty-four hours pre- 
 vious to that the usual bladder operation had been performed. On 
 the noon of the 23d, at 4 p. m., temperature 38; 24th, at 2:30 p. m., 
 39.7. Did not eat anything during the day. October 25th between 
 8 and 9 a. m., death ensued (43 hours after inoculation). 
 
 Autopsy at 2 p. m., October 25th. Region of inoculation shows 
 bloody suffusions and discoloration of the muscular substance. 
 Trachea and large bronchi, normal. Lungs pale, without presenting 
 anything striking. Intestines, mostly empty; small intestine filled 
 with a yellowish slime; in the ilium a very much swollen Peyer's 
 patch was observed. Liver not particularly large. No trace of 
 peritonitis or suppuration around the bladder. Spleen very much 
 swollen, firm. Kidney hyperemia 
 
 Bladder diphtheria very beautifully developed. 
 
 Small particles inoculated into two mice, which died on the 27th 
 October (within two days). 
 
 With this, the scarlatinal diphtheritic poison had been trans- 
 planted through two generations, and had retained its poisonous 
 properties. 
 
 Let us again study its nature in the diseased portions. Fine 
 sections from the bladder of Exp. xxiv show the following: 
 
 Viewed macroscopically, the diphtheria is present in little islets, so 
 that hemorrhagic inflammatory infiltrations alternate with coagula- 
 tion-necroses. These hemorrhagic inflammatory infiltrations still 
 show normal epithelium in some places. In others we find them 
 associated together with capillary haemorrhages and infiltrations in 
 the uppermost layers, also croupous membranes passing gradually 
 into the normal epithelium of the still healthy portion. Within the 
 dilated capillaries and veins (not certain without) we find accumula- 
 tions of bacteria of three different kinds: 
 
 1st. Globulus bacteria or micrococci, of about 0.7 pi diameter, 
 stained intensely in gentiana blue, or fuchsin; very pretty, especially 
 in some of the capillary loops of the most superficial mucous layers. 
 
 2d. Larger cocci of about 1.2 fx diameter, which throughout 
 stick together like biscuits, in twos, or chains of three and four, so 
 that they present the appearance of bacilli of from 2 to 3 /j. long, with 
 low powers of the microscope. 
 
 Fig. 6 conveys a very good idea of such formations. Several 
 capillaries, situated right in the midst of the diphtheritic patch, are 
 
EXPERIMENTAL DIPHTHERIA. 37 
 
 densely crowded with them. Fig. 6, b, shows them more highly 
 magnified. 
 
 3d. In the larger blood-vessels which still contain blood cor- 
 puscles, a third variety of micro-organisms seem to be present, 
 namely, bacilli of 1.8 pi in length, and 1 pi in breadth (measure- 
 ment not absolutely accurate), which, however, refused to be deeply 
 stained by any of the aniline colors, so that they were invisible 
 under ordinary illumination, and under diffused light appeared as 
 very minute and faint shadows. I am not quite certain whether 
 they are a peculiar species of organisms, or whether they are simply 
 those mentioned under the second head, very faintly stained. The 
 former seems to me more probable. 
 
 At any rate, we have here to do with a mixed infection, such as has 
 frequently been produced in the animal organism; and this mixed 
 infection was transmissible from the first diphtheritic scale to the sec- 
 ond. For even in the diphtheritic bladder of the second animal, these 
 different species of micro-organisms were present — though, perhaps, 
 not as abundantly, so far as the diphtheritic portions were concerned. 
 The latter is intelligible, because inoculation was undertaken, after 
 the disease of the mucous membrane had already progressed to the 
 end of the second day. 
 
 These three different kinds of organisms could also be demon- 
 strated in the kidneys of both of these animals. 
 
 So it seems pretty clearly made out, that the diseases produced 
 in this series of experiments are very closely connected with those 
 micro-organisms which may be regarded as identical with the poison 
 underlying the production of those diseases. The slimy exudation 
 in the throat in scarlatinal diphtheria also contains an inoculable 
 poison, which rapidly increases in quantity and, perhaps, virulence 
 within the body and produces a deadly and fatal disease, which can 
 be transmitted, and which produced death within sixty hours in 
 the first animal, and within forty-three hours in the second animal 
 inoculated with it. In this instance we have again shown that the 
 poison is especially collected and stored up in abundance in the 
 locally diseased organ. 
 
 Thus we have really and successfully produced, per synthesis, 
 the diphtheritic infectious disease — a disease of the animal body 
 characterized on the one hand by a general infection, and on the 
 other by a local process of coagulation-necrosis, and by an accumu- 
 
38 EXPERIMENTAL DIPHTHERIA. 
 
 lation of the poison at the place where the local disease takes place. 
 And now we are face to face with the diphtheritic poison in the shape 
 of these micro-organisms. 
 
 There remains, however, now to add to this, that in the human 
 subject the taking up of these bacteria alone is sufficient to 
 produce the disease, both local and general, while the animal mucous 
 membrane does not respond by that peculiar inflammatory condition 
 to the action of these micrococci. This condition must be produced 
 artificially. 
 
 Before we consider these questions more in detail, we will first 
 record two more experiments which were made on the diphtheritic 
 animal of Experiment XXV. Besides the above mentioned inocu- 
 lation of two mice with the diphtheritic membrane ofthe animal in 
 question, two more inoculations were carried out as follows, on Octo- 
 ber 25th, 1882: 
 
 1. Experiment XXVII. — A strong, brown-red rabbit received, 
 subcutaneously, a certain quantity of the patch in the right side of 
 the back, all the necessary precautions of heating all the instruments 
 having been observed. 
 
 2. Experiment XXVIII. — The ears of a somewhat smaller 
 rabbit were inoculated with a bit of the patch. 
 
 Both animals became very feverish, which condition lasted six 
 days, or until October 31st, in each one of them. The temperature, 
 taken daily at 3:00 p. M.,was always over 40.0 C; the highest temper- 
 ature in No. 27 was 41. o° C; in No. 28, 41.4° C. Appetite bad. In 
 the beginning of November the temperature was again normal (39 
 to 39.5 ). They appeared to be very well again, and No. 28, the ani- 
 mal which had simply been inoculated, remained entirely well. It 
 died towards Christmas, sometime after all abnormalities due to its 
 inoculation had disappeared. 
 
 No. 27, however, the animal which had received the sub- 
 cutaneous injection, was found on November 10th with a purulent 
 pan-ophthalmia of the right eye and a purulent discharge from the 
 nose. The wound on the back had opened and now showed a rather 
 extensive pus cavity. The eye gradually dried up, but the nasal 
 catarrh remained ;' the animal was often seen eating. On Nov- 
 ember 25th, it having still eaten in the morning, it was found dead in 
 its cage in the afternoon. 
 
 Autopsy was made on the afternoon of November 26th. At the 
 
EXPERIMENTAL DIPHTHERIA. 39 
 
 place of the wound there is a pus cavity ; right eye dried up. The 
 mucous surface of the soft palate and pharynx were in a condition 
 of purulent catarrh and covered with pus. Larynx and trachea free. 
 Purulent bronchitis in both lungs. A large number of scattered 
 abscesses. Pleural cavities free. Heart normal. No peritonitis. 
 Spleen, liver and kidneys apparently normal. 
 
 This last experiment is remarkable. The animal became fever- 
 ish just exactly as did the other animal which had simply been 
 inoculated ; this was regarded as the result of an infectious disease 
 analogous to that from which animal No. 25 died, with this difference, 
 however, that the fever was much lighter here than in the previous 
 case, and both animals survived. But now a pus cavity formed at 
 the end of a week at the place of inoculation and from it the 
 pysemic infection from which the animal died took its start. It 
 seems very probable that this animal, on the 25th of October, received 
 into its system two infectious poisons, one of which was the cause of 
 the fever, the other the cause of the pyaemia, which appeared much 
 later. It is much less probable that some extraneous poison had been 
 introduced in the operation, for, of a number of animals operated on 
 at the same time, this was the only one so affected. 
 
 It will be remembered that just in that infectious disease of 
 animals 24 and 25 there were found two or three different kinds of 
 bacteria in the blood-vessels of the diseased bladder. These differ- 
 ent poisons must then have originated from the mouth of the child 
 suffering with scarlatina, from which the original material for inocu- 
 lating the rabbit had been taken. 
 
 But which one is now the diphtheritic poison? Are we to look 
 upon it as the cause of the six days' fever following the inoculation ? 
 It cannot be identical with a pyaemic poison. 
 
 With these doubts we have arrived at a question, the discussion 
 of which has already been engaged in by many observers, but the 
 solution of which would finally decide all experiments with infectious 
 poisons hitherto made. 1 
 
 Is the infectious poison which is contained in the diphtheritic 
 patches in the throat of a man suffering with the disease, really of 
 
 1 With the single exception of the experiments of Klebs (Archiv. f. exp. Pathologie Bd. 
 iv. s. 238), and Rosenbach (Virchow Archiv. Bd. lxx, 1877, 2 Heft), who did not take the mate- 
 rial for the infection out of the mouth. But their results were not sufficiently clear, and their 
 conclusions were not indisputable. 
 
40 EXPERIMENTAL DIPHTHERIA. 
 
 a diphtheritic nature, or does it belong simply to one of the septic 
 poisons of which, as has been demonstrated by Koch's experiments, 
 we have not only one but a great many ? 
 
 This question, very unfavorable to the theory of the specific 
 nature of diphtheria, could be readily answered, if it could be 
 proven that quite similar infectious conditions could be produced 
 by the introduction into the system of the mucous secretion of men 
 not suffering from diphtheria, or such as are entirely well, as 
 are produced by inoculation of such secretions from men suffering 
 with diphtheria. 
 
 This has already been experimentally proven. After Dr. 
 Renaud and Lanmelongue 1 had produced a transmissible infectious 
 disease by a subcutaneous injection of saliva from a child dead with 
 lyssa into a rabbit, Pasteur 2 found that an analogous infectious dis- 
 ease could be induced in the same animals by inoculating them with 
 the saliva of children who had died with catarrhal pneumonia. 
 Koch 3 is convinced that this infectious disease with its malignant 
 oedema, may be induced by bacteria coming from different places. 
 Soon after, Vulpian succeeded, *by injection of saliva from healthy 
 men into rabbits, in producing a disease from which they soon died, 
 and in which the blood contained many micro-organisms of which 
 several resembled those of Pasteur ; and a drop of such blood, diluted 
 with water, sufficed to produce the disease in another animal. This 
 disease in question was, then, a genuine septicaemia. 
 
 I further find in a communication of Dr. Kiihn 5 in Moringen, 
 the following remarks : Fresh and healthy human saliva, injected 
 into rabbits may cause septic fever and metastatic abscesses. 
 
 In order now to form for myself a correct idea of these facts, I 
 undertook the following experiments: 
 
 Experiments XXXIII — XXXVI.— At 3 p. m., December 
 27th, 1 88 1, a turbid, slimy fluid was taken from the back part of 
 the tongue of a perfectly healthy man, and small quantities of it were 
 placed under the skin of the four rabits, wounding at the same 
 time the muscular fascia; the wound was immediately sewed up. 
 
 1 Bulletin del'Academie I. m. Stance, der i et der 8 Fcon, 1881. 
 
 2 Ibidem Commemoration of Perrot. Stance du 22 Mars 1881. 
 
 3 Gaffky, Mittheilungen d. Kaiserliche Gesundheits Amtes Bd. i S 93 fig. 
 
 4 Bulletin etc. Stance du 29 Mars 1881. 
 
 5 Berliner Klin. Wochenschrift, 19 Sept. 1881, No. 38 S. 547. 
 
EXPERIMENTAL DIPHTHERIA. 41 
 
 Every one of the rabbits died between the fifth and ninth days 
 after infection, with the following symptoms: 
 
 Rabbit No. 35. — Temperature on day of inoculation, 39 C; 
 December 29, 4o.°C; December 30, 40. 7 C; December 31, 40. 8° C. 
 On the morning of this day an abundant purulent nasal discharge was 
 discovered. 
 
 During the night of December 31st the animal died. 
 
 Autopsy at 1 p. m. The skin of the whole of the right side 
 was found undermined by an extensive abscess, containing bad- 
 smelling, cheesy, purulent masses. Muscles at place of inoculation 
 of a dirty red color. Spleen distinctly enlarged, brownish red, and 
 firmer than normal ; capsule moderately dense. Kidneys hyperaemic 
 Nothing abnormal about the liver. Bladder normal. Lungs and 
 pleura normal. 
 
 Rabbit No. 37. — Temperature at day of inoculation, 38.9 ; 
 December 29, 39.5 ; December 30, 39.6 ; December 31, 39.3 ; 
 January 1, 39.6. Died during the night from the 1st to the 2d of 
 January. Rest same as in No. 35, only more extensive. Abscess 
 reaching from the crest of the ileum to the clavicle. Spleen not 
 swollen. 
 
 Rabbit No. t,^. — Temperature at day of inoculation 39. 3 C; 
 December 29, 40 C; December 30, 40. i° C. A purulent nasal dis- 
 charge noticed on this day. Isolation December 31, 40. o° C; Jan- 
 uary 1, 38. 8° C. Died during the night. 
 
 Autopsy January 2d, at noon. An extensive abscess was formed, 
 reaching up clear under the scapula. Spleen somewhat large and 
 thickened. Trachea, lungs and pleura normal. General fibrin- 
 ous purulent pericarditis. Intestines very much distended, mucous 
 membrane strongly injected. 
 
 Rabbit No. 34. — Temperature at day of inoculation 39.4 ; 
 December 29, 40.0 ; December 30, 41.2 ; Dec. 31, 40.7 ; January 1, 
 40.0 ; January 2, 39.5 ; January 3, 38.8. Found dead on January 
 5. Enormous pus cavity along the entire right back. In the upper 
 left and lower right lobes of lungs some thickened hemorrhagic 
 spots. In both auricles and in the right ventricle large clots. 
 Spleen scarcely swollen. 
 
 In accordance, then, with the statements of Kiihn, we obtained 
 within a very short time, as the result of the introduction of small 
 quantities of fluid from the mouths of healthy human beings under 
 
42 EXPERIMENTAL DIPHTHERIA. 
 
 the skin of rabbits, extensive pus formations at the place of inocula- 
 tion, and even by metastatic abscesses in the body of the animal. 
 
 An examination of the contents of the abscess showed that in all 
 these inoculations bacteria played an important role, for it consisted 
 principally of detritus and micro-organisms of various forms, as 
 globular bacteria, scattered and in groups, and bacilli, long, short, 
 broad, and narrow, while pus corpuscles were rare. The process 
 was rather one of advancing necrosis than of pus formation. Groups 
 of lymph-cells were also found in the blood of these animals. These 
 cells contained in their immediate surroundings small granules very 
 distinctly stained with methyl blue. It was, however, difficult to 
 decide whether they were not Ehrlich's nuclei of mast cells. 
 
 It was not my purpose to follow out these interesting results, but 
 they proved valuable as additional proof of the danger of saliva to 
 rabbits, and to show that it contains bacteria which may become 
 pathogenic in the animal organism. 
 
 But what do all these new facts tend to prove ? What does it 
 signify that inoculations with saliva sometimes produce malignant 
 oedema, sometimes septicaemia, 'sometimes progressive necrosis, and 
 sometimes pyaemic metastases in the rabbit ? 
 
 This question can only be answered in one way, and that is, that 
 in the buccal cavity of the healthy man we find various species of 
 bacteria, which again vary in different individuals, and in the same 
 individual at different times, both in shape as well as in their mode 
 of action. These bacteria introduced into the circulation of certain 
 animals, cause their death; they possess, however, no pathogenic sig- 
 nificance for the human organism, at least not so long as they are 
 only in the cavity of the mouth, on the most superficial layers of 
 the epithelia. 
 
 If it is, then, certain that we find these bacteria in the cavity of 
 the healthy mouth, how much more may we expect to find in a dis- 
 eased buccal cavity, additional ones, perhaps new ones, which may 
 perhaps have displaced the former ones, since with the disease a 
 change in the conditions for the subsistence of the minute organ- 
 isms has naturally been brought about. This is especially true of 
 the croupous diphtheritic affection of the mucous membrane of the 
 mouth. Here arise, in the place of the original epithelium, the upper- 
 most strata of which certainly do not offer a very rich albuminous 
 substratum, extended fibrinous masses, coagulated albuminous masses, 
 
EXPERIMENTAL DIPHTHERIA. 43 
 
 which, in the moist and warm atmosphere of the mouth cavity, offer 
 a very different soil for the development of these micro-organisms. 
 The fact that in such a soil bacteria may arise, which are different 
 from those occurring in the normal cavity of the mouth, is not strange. 
 It is not less easily understood that such new species, when inocu- 
 lated into the proper animals, give rise to different forms of infective 
 diseases than are procured by inoculation of normal saliva, that per- 
 haps even two or three different disease processes may be inaugur- 
 ated in the same animal (as I obtained on inoculation with mucus 
 from the scarlatina patient). 
 
 Thus, we are now in a position to state positively, that these in- 
 fections or inoculations with bacilli, as I obtained them from the 
 slimy masses of primary diphtheria as well as from the mouth of the 
 scarlatina patient, stand in no relation whatever to the diphtheria or 
 scarlatina, as they occur in human subjects; these organisms were 
 simply accidental, and happened to find a good soil for their devel- 
 opment in the changed mucous membrane. 
 
 All experiments hitherto made with the diphtheritic secretion 
 from the mouth of persons sick with the disease have, therefore, 
 lost a great deal of their original value. No one is capable to 
 declare, or justified in asserting that he has, in the manner above 
 described, inoculated either scarlatina or diphtheria from one ani- 
 mal into another, no matter where the inoculation was made, 
 whether in the trachea or in the subcutaneous cellular tissue, and no 
 matter what was the course and character which the disease thus 
 produced took on. 
 
 One cannot deny that these deductions are quite justifiable. 
 But they are not entirely free from objections, inasmuch as they rest 
 on a proof of simple probability. One may admit that in a healthy 
 mouth cavity a number of bacteria accrue, which have nothing to do 
 with the poison of diphtheria, but which are rather of a septic char- 
 acter. But, does this disprove the possible fact that, side by side 
 with these septic bacteria in human diphtheria, there is the real, 
 genuine micro-organism of diphtheria? And is it not at least very 
 probable that it is just that short bacillus, which from the surface 
 of the diphtheritic membrane is so easily transportable (retaining 
 its form) to the animals, and whose shape distinguishes it so well 
 from that of other animals, that this is not the septic bacillus but the 
 true representative of the diphtheritic poison ? Certainly we cannot 
 
44 EXPERIMENTAL DIPHTHERIA. 
 
 deny the possibility of the presence of the representative diphtheritic 
 poison among the numerous species of bacteria which have been 
 described as occurring in the mouth of those suffering with diph- 
 theria, and this possibility even my experiments are unable to dis- 
 prove; it only remains to be added that this peculiar micro-organism 
 has not yet been identified, and that with the methods at present at 
 our command it cannot be identified. 
 
 Then the second question, if perhaps that short bacillus be the 
 representative bacillus to which 'the diphtheritic disease was due, 
 can be answered in the negative both as a result of my experiments 
 and as a deduction from the following line of thought. 
 
 The poisonous effect which this bacillus produces, when inocu- 
 lated in the animal, is due to its enormous increase in the blood. 
 This is simply and distinctly shown in the fact that in all cases of 
 death it can be found in vascular districts of the most different 
 kinds, far from the place of inoculation, but more copiously in the 
 blood-vessels of the diseased mucous membranes. 
 
 But in those places the presence of these micro-organisms is 
 easily proven by means of our methods of staining. 
 
 If, then, this poison was identical with that of human diph- 
 theria, the general diphtheritic infection in the human subject would 
 have to be represented as due to a copious and abundant increase of 
 this bacillus in the blood, no matter how it got there, and that 
 thereby life was destroyed. And here also would we expect to find 
 a particularly abundant accumulation of bacilli in the diseased 
 mucous membrane. 
 
 Consequently, in those cases of diphtheria in man, where death 
 was not due to the mechanical effects of the disease (suffocation) but 
 to the general infection (collapse, asthenia, paralysis of the heart, 
 nephritis), the blood-vessels of the diseased mucous membrane, 
 the capillaries of kidney and liver, etc., ought to be filled with 
 bacilli. 
 
 The presence of these bacilli in the human system ought to be 
 capable of proof, according to the same method, and in as easy and 
 positive a manner as this is done in animals in every respect. 
 
 In this we do not succeed. Entire series of sections of the uvula, 
 of the throat, kidneys, etc., of patients dead of diphtheritic in- 
 fection, have been treated with gentiana violet, fuchsin, Bismarck 
 brown (also in alkaline dyes), without succeeding in dis- 
 
EXPERIMENTAL DIPHTHERIA. 45 
 
 covering a single bacterium, which, on the diseased surface of the 
 mucous membrane, are so easily made out. Consequently the diph- 
 theritic poison has nothing to do with the so-called " pilzrasen " (a 
 much abused and often cited term) which covers the diseased 
 mucous membrane of the cavity of the mouth. 
 
 Therefore, then, the diphtheritic poison is as yet unknown, 
 as are numerous other disease-poisons, e. g. that of scarlatina, of 
 measles, of small-pox, etc. The diseases I produced in my inocu- 
 lation experiments, were, it is true, diphtheritic, in so far as they for 
 the first time represented undoubted combinations of a local diph- 
 theritic disease of the mucous membrane and a general infectious 
 disease; but still the infectious poisons used were not identical with 
 the poison in human diphtheria, but were entirely of a heterogeneous 
 nature. 
 
 I do not hesitate to acknowledge this negative result, to whicn 
 my second series of experiments and the train of thought to which 
 these gave rise, have led me, for it is not a step in the wrong direction 
 in the search for truth, to recognize an error and to publicly acknow- 
 ledge it. We do not, therefore, give up hope that the diphtheritic 
 virus may not some day be discovered, it will, in all probability, re-. 
 quire entirely new methods in order to be successful in such a 
 search. 
 
 In the case that the general infection in diphtheria be produced, 
 as is very probable, by micro-organisms increasing rapidly in the 
 blood, then all of our attention would have to be directed to the dis- 
 eased blood vessels of the affected mucous membrane and to their 
 contents. It would be there where we would have to look for an 
 accumulation of the poison, according to my experiments. 
 
 For those who are convinced that the poison of diphtheria is 
 even now not discovered, another question remains to be answered, 
 and a question which, by many physicians, is generally looked upon 
 as settled, namely, whether the poison first finds a place on the sur- 
 face of the mucous membrane, and thence makes its way into the 
 blood, or whether the diseased mucous membrane is a second- 
 ary localization which follows a primary infection of the 
 blood. From my experiments on the condition for the local diph- 
 theritic process in the mucous membrane, it follows that the pro- 
 found change in the tissues underlying it all might just as well be 
 produced by some noxious agent circulating in the blood as by one 
 
46 EXPERIMENTAL DIPHTHERIA. 
 
 finding its way from the surface of the mucous membrane into the 
 interior. 1 I can add nothing more for the solution of this important 
 problem from my experimental research, and cannot therefore go 
 any further. 
 
 1 As analogies we may cite the diphtheritic patches which arise in some places on mu- 
 cous membranes after injections of corrosive sublimate or arsenic. 
 
EXPLANATION OF PLATE. - 
 
 Fig. I. — Formation of haemorrhagic oedema and diphtheritic patch in 
 mucous membrane of bladder of rabbit. 
 
 The picture represents a fine section from the fundus of a rabbit's bladder 
 which had been subjected to treatment with the ligature, as was described in the 
 text, 48 hours before the animal was killed. 
 
 Stained by eosin and gentiana-violet. 
 
 Magnified— Zeiss CC. Oc. I. 
 
 The portion on the right is in a condition of haemorrhagic oedema ; only 
 part of the much swollen submucosa is visible and, within it, several engorged 
 blood-vessels. The epithelium is much swollen up and cedematous, and, as the 
 mucosa, studded with extravasated blood corpuscles. 
 
 The portion on the left is the diphtheritic eschar ; epithelium, mucosa, 
 submucosa, cells, vessels, etc., have become changed into a homogeneous 
 mass, stained red with eosin, within which only a small amount of nuclear 
 detritus (stained blue) is to be seen. 
 
 Fig. 2. — Beginning coagulation-necrosis of the epithelium. From the 
 bladder of a rabbit, killed 24 hours after the removal of the ligature. Boiled 
 preparation. Stained with eosin and gentiana-violet. Mag. Zeiss F. Oct. I. 
 1-410 (not 1-490 as it says on plate.) 
 
 Only portion sharply focussed is the one in which the exudation has 
 thoroughly penetrated the epithelia. Some of the cells, whose nuclei have 
 ceased to be stainable, are pressed apart by the coagulated exudation, which 
 latter has taken on a deep-red stain. 
 
 Fig. 3. — Croup of mucous membrane of bladder. 
 
 The rabbit from which this specimen was taken was killed six days after 
 the removal of the ligature. 
 
 Staining by gentiana-violet. Magn, Zeiss CC. Oc. I. 
 
 One sees a fragment of croupous membrane still adhering to the under- 
 lying mucous tissue. The limit is marked by the blue stain which the mucous 
 tissue has taken up and which has arisen from a very dense infiltration of nuclear 
 detritus (not of normal lymph cells.) 
 
 Within the croupous membrane numerous nuclei of emigrated cells. 
 
 Epithelium is missing throughout. 
 
 Fig. 4. — Diphtheritic eschar, within which blood-vessels, still pervioust 
 are found. 
 
 Animal killed three days after removal of ligature, at the end of the second 
 day, had been inoculated with bacillus anthrax, from which inoculation it died 
 towards the end of another day. The swelling of the diphtheritic portion of the 
 mucous membrane was very great and intensely haemorrhagic. Post mortem 
 was made immediately after death and the bladder put into absolute alcohol. 
 
 Staining with eosin and gentiana-violet. Magn. Zeiss CC. Oc. IV. 
 The staining by eosin on the slide is much deeper than is represented 
 in the picture. Nothing more can be seen of the original mucous tissue 
 
48 EXPERIMENTAL DIPHTHERIA. 
 
 (this portion, two days earlier, would have presented the appearances of the right 
 half in Fig. i). 
 
 The portion included between the violet line and the adjoining brownish- 
 red line, is the transformed epithelial layer; all the rest is mucous and sub- 
 mucous tissue that has undergone coagulation-necrosis. The brownish-red 
 stained portion has originated from the haemorrhagic part at the diphtheritic 
 eschar. In that slightly granular homogeneous tissue a few nuclei from emi- 
 grated cells may be seen. 
 
 In the midst of this eschar several open channels filled with bacilli 
 anthracis are seen. The greater portion of the walls of these channels is stained 
 red; they are without nuclei, and may be looked upon as dead. Some nuclei 
 are, however, visible in the wall of the larger vessels on the right — an arrange- 
 ment which marks this vessel as a small artery. 
 
 In all these dead blood-vessels, circulation must have been still going on 
 a few hours before death took place, as may be supposed, from the abundant 
 presence of bacilli in them. 
 
 Fig. 5. — Accumulations of micro-organisms (from the mouth of a diph- 
 theritic patient) in the capillaries of the diseased bladder. 
 
 Section from the bladder of a rabbit which had been inoculated with the 
 slime from a diphtheritic tonsil, and in which death occurred three days after 
 the inoculation; a portion is chosen which shows ihe epithelium in a condition 
 of haemorrhagic cedema. Illumination with Abbe's condenser without dia- 
 phragm. 
 
 Staining with Fuchsin. Magn. Zeiss J. Oc. II. 
 
 Two capillaries are seen densely crowded with small bacilli. 
 
 Fig. 5. — Shows these bacilli on a more enlarged scale (Ziess J. Oc. IV). 
 
 Fig. 6.— Accumulations of micro-organisms (from the mouth of a scar- 
 latina-diphtheritic patient) in the capillaries of a diphtheritic eschar of the urinary 
 bladder. 
 
 Section from a diphtheritic patch of the bladder of a rabbit which had 
 been inoculated with slime from a scarlatina-diphtheritic patient, and which died 
 three and one-half days after that inoculation. 
 
 Illumination and focussing same as in previous preparation. 
 
 Staining with Fuchsin; in the preparation more violet than blue. Magn. 
 Zeiss J. Oc. II. 
 
 Capillaries crowded with micro-organisms, still visible within the patch. 
 
 Fig. 6. — Shows that these seeming bacilli are micrococci, arranged in 
 pairs or chains. 
 
.:&i 
 
 A 
 
 
 ©g^PP 
 
 %. 
 
 410. 
 
 '*>V»' 
 
 490. 
 
 F i B. 'i 
 
 4-, 
 
 Iji; 
 
 i¥ v 
 
 
 - *t^>i "^ 'J' 
 
 
 
 
 Si? 
 
 
 
 •**7 
 
 CoiUTl 
 
APPENDIX. 
 
 This appendix embraces, in abstract form, a paper on diph- 
 theria, read " by Dr. Gerhardt, of Wiirzburg, before the German 
 Medical Congress, which held its session last year in Weisbaden, 
 and also the discussion on diphtheria which followed, and which 
 was entered into by Klebs, Heubner and all the prominent delegates 
 there. 
 
 Dr. Gerhardt. — Diphtheria is an infectious disease. Abun- 
 dant proof of this has been produced both clinically and experi- 
 mentally. The poison of diphtheria has, moreover, the property of 
 remaining alive and effectual for a certain length of time, at 
 ordinary temperature, outside the animal body, and can be carried 
 in clothing and adhere to houses and the walls of rooms. Observa- 
 tions are on record apparently tending to prove that the diphtheritic 
 poison has gained entrance into the human body through food, 
 (milk, etc.) The poison is furthermore transmissible from man to 
 animals, and Dammann has described a diphtheria among calves ; 
 and perhaps also from animals to man as Dr. G. seems inclined to 
 believe from the following remarkable circumstance which was 
 brought to his notice: 
 
 " In the village of Messelhausen, near Landa, in Baden, a 
 chicken farm had been started, into which 2,600 chickens had been 
 brought from the country near Verona, Italy. A few of these had 
 diphtheria and, within the first six weeks 600 of them died of the 
 disease, and later on 800 more. The following summer 1,000 
 chickens were hatched from eggs laid by these hens and all of these 
 died of diphtheria within the first six weeks. Five cats succumbed 
 to the same disease at this farm, and a parrot also took the disease 
 but was saved. In November, 1881, an Italian rooster, about to 
 be touched up with carbolic acid, bit one of the attendants in the 
 left hand and foot. The man was taken sick with high fever and 
 both wounds were covered with diphtheritic membranes. The 
 wounds healed very slowly, the disease lasting in all three weeks. 
 Two-thirds of all the farm hands became affected with diphtheria 
 
 §4 
 
50 EXPERIMENTAL DIPHTHERIA. 
 
 of the throat, and pharynx and, at the same time, not a single 
 case occurred in the adjoining village." 
 
 Diphtheria may be said to be always accompanied by fever, or 
 at least those cases in which no fever is present are exceedingly rare. 
 This fever differs in many respects from that accompanying other 
 infectious diseases. Thus we find that in many infectious diseases 
 as in variola, measles, etc., the original fever is caused by a peculiar 
 process of infection which takes place in the blood, and which is 
 characteristic of these diseases ; and that, on the contrary, certain 
 periods of fever which supervene later on, as for instance, the fever 
 of suppuration, the fever of decrustation in variola, those forms of 
 high fever occurring in parotitis when the testicles become impli- 
 cated, are independent of the original fever. It is very different 
 with diphtheria. Here the fever is directly dependent upon the 
 local affection and the rule may as well be stated here that, as 
 long as the local affection keeps on increasing the fever will 
 also increase, and that as soon as this ceases the fever will also 
 cease. 
 
 Glandular swelling in diphtheria is directly dependent on the 
 passage of the poison into the lymphatics and into the economy at 
 large, and its traces may, moreover, be discovered in the subsequent 
 rheumatoid affections, in nephritis, endocarditis, peripheral nerve- 
 lesions and other allied affections. Into this category also belongs 
 that peculiar form of anaemia, characterized by great feebleness of 
 the heart's action with great increase in the pulse rate, which by some 
 is looked upon as a paralysis of the vagus, and by others is interpreted 
 as a fatty degeneration of the heart. 
 
 In diphtheria it is especially necessary to differentiate, 
 and the microscope will, no doubt, prove the best means of 
 doing this, for with it we can discover the infectious agent. But, 
 since the time has not yet arrived when every physician is expert 
 enough to make this sort of differentiation applicable to all cases, it 
 would be premature to recommend it. 
 
 So far as age is concerned, although diphtheria may .attack 
 new-born infants, the first year of life is almost exempt from the 
 disease; it is most liable to appear between the first and fifth year of 
 life. Moreover, diphtheria has a stage of incubation of an indefinite 
 length of time; according to H. Roger, it is between two and seven 
 days, according to others, it may be fourteen days. One of the most 
 
EXPERIMENTAL DIPHTHERIA. 5 I 
 
 important features, according to Dr. G., is that the stage of incuba- 
 tion is indefinite as to length of time. He calls attention to the fact, 
 that certain infectious diseases, more especially those which termi- 
 nate in a crisis, also have a stage of incubation of a definite length 
 of time, as, for instance, typhus, measles, variola; and that certain 
 others, in which recovery takes place by lysis, have a stage of incu- 
 bation of an indefinite length of time, such as typhoid and scarlatina; 
 he seems to be inclined to believe that this stage of incubation and 
 mode of recovery stand in direct relation to the origin, growth and 
 decay of the organisms which cause these diseases. Diphtheria 
 belongs to that class of infectious diseases Which have an incubation 
 of indefinite duration, as well as an indefinite febrile stage, and which 
 terminate in lysis. 
 
 Diphtheria is characterized as an infectious disease, not only in 
 a general sense, but also from the fact that certain micro-organisms 
 have been discovered in connection with it. Observations of this 
 kind have been made by a great many observers, such as Tommasi, 
 Letzerich and others. Nor is it difficult in the least to discover 
 micro-organisms in diphtheritic membranes; anyone who has given 
 the subject his serious attention, must have succeeded in con- 
 vincing himself of this fact, and acknowledge that the real difficulty 
 lies in the great mass of them, and in the decision as to which one 
 of these organisms is the primary cause of .the disease. Every 
 writer on the subject believes his own to be the right one; others 
 have come to the conclusion there must be several of them cooper- 
 ating to produce diphtheria. This is not at all unlikely, and it would 
 require no great stretch of the imagination to think that several 
 forms of micro-organisms might be causative of diphtheria. Indeed, 
 in consideration of the multiplicity of forms of diphtheria occurring 
 in everyone's practice, we are almost forced into the belief that there 
 must be several distinct varieties of micro-organisms which cause 
 the disease, and that the different forms, and the different degrees of 
 severity, of cases of diphtheria are directly dependent on the differ- 
 ent forms or combinations of forms of micro-organisms. 
 
 Diphtheria becomes more especially localized on the gullet and 
 throat, and this predilection for the mucous membrane in this situa- 
 tion alone, would lead us to expect certain anatomical conditions in 
 these situations which are peculiarly favorable to such localiza- 
 tion. Ph. Stohr, of Wiirzburg, from some investigations on this 
 
52 EXPERIMENTAL DIPHTHERIA. 
 
 subject, has shown that, on the surface of the tonsils, the epithelia 
 show cracks or minute loop-holes through which round-cells emi- 
 grate. If it is true, as has been demonstrated in a very convincing 
 manner by Dr. Riihle, that the stratum corneum of the skin and mu- 
 cous membrane presents an impenetrable barrier to the passage of 
 micro-organisms, the above anatomical peculiarities of the mucous 
 membrane of the tonsils seems to create an exception to this rule. 
 
 According to what has been said, it will be seen that Dr. Ger- 
 hardt shares the belief that diphtheria is caused by micro-organisms, 
 and that they find their way into the economy principally through 
 mucous membrane of the throat, though other channels may be open 
 to them. The. treatment which he principally recommends may, 
 therefore, be anticipated, and consists mainly in the attempt to dis- 
 solve away the membrane and thoroughly disinfect the throat. He, 
 however, speaks discouragingly of the application of anything that is 
 irritating to the throat and which may produce inflammation, for in- 
 flammatory foci present a condition of things which is always favor- 
 able to the implantation of micrococci. Little weight, if any, is laid 
 upon constitutional treatment. . 
 
 Klebs expresses himself as extraordinarily pleased with the 
 clinical results obtained by Dr. Gerhardt, and states that he has ar- 
 rived at almost the same conclusions, although in an entirely different 
 manner. This has reference, more especially, to the composite char- 
 acter of diphtheria. He then enumerates various disease-processes 
 which are accompanied by the promotion of fibrinous membranes, 
 such as dysentery, diphtheria of the bladder, croupous affections of 
 the lungs, which are non-infectious, and, therefore, to be excluded 
 from under the term diphtheria. The researches of Oertel, Eberth, 
 and himself, have sufficiently demonstrated the infectious nature of 
 genuine diphtheritic membranes and their transmissibility to the 
 cornea. From extensive examination of membranes from cases of 
 diphtheria met with in Prague, and which were characterized by 
 great gravity and prominent nervous symptoms, with hemorrhagic 
 formations on brain and spinal cord on post-mortem examinations, 
 he obtained specimens, some of which were exhibited, in which 
 some very peculiar micro-organisms were found. From the fact that 
 they were transmissible to the cornea, he concluded that they 
 were the organisms to which the disease was due and designated 
 them as the " microsporon diphtheriticum," which, like microsporon 
 
EXPERIMENTAL DIPHTHERIA. 
 
 53 
 
 septicum, have the peculiarity of showing two different stages of devel- 
 opment, that of bacilli and round, globular micrococci. 
 
 Later on, however, in Zurich, cases of diphtheria occurred which 
 were evidently of an entirely different character from those that had 
 come under his observation in Prague. The membrane of the 
 throat, in these cases, had a great tendency to extend into the 
 trachea, and life was generally terminated in that way, but also, 
 sometimes, through collapse. These cases were also found to be ac- 
 companied by albuminous urine, and disease of the kidneys was 
 suspected, but the suspicion was not sustained for the reason that the 
 symptoms of uraemia were wanting. Search was made for micro- 
 organisms and they were found, but of an entirely different nature 
 from those found in former cases, namely, instead of their being 
 globular, they were exclusively bacillar formations. The two forms 
 of diphtheria which Klebs distinguishes, had their origin in this way. 
 The one is the diphtheria micro-sporon, and the other the diph- 
 theria bacillaris. 
 
 As further anatomical changes which are peculiar to the bacillar 
 form of diphtheria, he gives the following: Only very light enlarge- 
 ment of the spleen, if any; no parenchymatous degeneration of the 
 kidneys, and no changes in the heart and liver; those dying from it 
 generally do so from severe lung affection. The microscopical 
 examination of such lungs generally shows very extensive interstitial 
 deposits : interstitial diphtheritic pneumonia. 
 
 This lung affection generally takes on a chronic course, and 
 keeps on long after the diphtheria has entirely disappeared. 
 
 The characteristics of the bacillar diphtheria are summarized 
 as follows : 
 
 i. Fibrinous exudation on tonsils, with great tendency to 
 extend into the trachea. 
 
 2. Constant presence of a definite form of bacilli on the 
 diseased mucous membrane, which are primarily developed within 
 the epithelial cells, and giving rise to the fibrinous exudation as a 
 consequence of a peculiar paralysis of the blood-vessels. 
 
 3. High fever, which accompanies the extension of the 
 fibrinous exudation but which ceases later on, and only recurs on 
 the occurrence of septic infection. 
 
 4. Interstitial inflammatory processes in internal organs, as 
 sequelae, as it seems, not, however, as much dependent on the pres- 
 
54 EXPERIMENTAL DIPHTHERIA. 
 
 ence of micro-organisms within these organs, as on extensive 
 changes taking place in the blood-vessels (interstitial pneumonia, 
 myocarditis, neuritis, albuminuria, and interstitial nephritis). 
 
 5. Necrotic decomposition of the membrane leads to septic 
 complications which may cause death long after the diphtheritic 
 process in the throat has come to an end. 
 
 Heubner. — The experimental study of diphtheria has evi- 
 dently to deal with two problems. The first is that of the peculiar 
 local affection of human diphtheria, and the second is that of the 
 general infection. No experiment can be called complete that does 
 not fully answer to these requirements. The attempt to produce 
 both these conditions by one experimental manoeuvre did not seem 
 to be successful. I, therefore, attempted to deal with these two 
 problems separately, by first trying to produce the local disease, and 
 by superadding to this, later on, the general constitutional part of 
 the disease in question. 
 
 By thus producing an artificial diphtheria by synthesis, in ani- 
 mals, no doubt there was a strong possibility that some advance in 
 oar knowledge of human diphtheria might be made. 
 
 The method of inducing the local disease which had hitherto 
 been in practice, and which consisted in the application of caustics 
 to mucous surfaces, impressed me as being too crude. - While en- 
 gaged in the study of the investigations of Cohnheim and Litten, it 
 occurred to me that it might be possible that those severe inflamma- 
 tory processes by which certain tissues, the testicle and kidneys, 
 responded to a temporary interruption of the blood current, might 
 also be produced in the mucous membrane, and these might prove 
 to be morphologically identical with diphtheria. This hypothesis 
 was afterwards confirmed, as soon as the proper mucous tissue had 
 been found, in which such a temporary interruption to the blood 
 current could be brought about. The mucous membrane of the 
 throat could not be made use of, for neither dogs nor cats possess 
 uvulas. After looking around a good deal it was found that the 
 urinary bladder of the rabbit proved to be the best object for exper- 
 imentation, and in which a temporary arrest of the blood-current 
 could well be brought about. It was comparatively easy to cause a 
 sudden arrest of the blood current, and maintain it by a ligature 
 around the fundus, and above the entrance of the ureters, which 
 ligature could be removed again very easily and the circulation 
 
EXPERIMENTAL DIPHTHERIA. 
 
 55 
 
 be allowed to be resumed, the blood made to re-enter the area of 
 vessels thus treated. 
 
 After such an operation it was found that, during the first day, 
 the mucous tissue became hsemorrhagico-cedematous; during the 
 second day this fluid oedema began to coagulate, and on the third 
 day a picture, identical with that of diphtheria, presented itself and 
 could easily be recognized. 
 
 It is, therefore, very evident, after a careful study of the condi- 
 tions which are causative of this local disease, that Cohnheim's post- 
 ulate is hereby fully confirmed, namely, that it is the result of a super- 
 vention of necrosis upon inflammation. The moment the epithelium 
 looses its nuclei, coagulation within and upon the mucous tissue 
 begins to set in. These two conditions, then, must be considered 
 as the causative ones of the local part of diphtheria. 
 
 In order, now, to dispose of the second problem, an infectious 
 disease was produced in an animal whose bladder had already been 
 rendered locally diphtheritic, and in order to facilitate study on 
 this point, the poison of anthrax, so easily recognized, was employed. 
 Animals were inoculated at different periods of the progress of the 
 development of the local disease, so that its influence might be 
 studied early as well as late in relation to the local disease. 
 
 The anthrax poison accumulated in those locally diseased tissues 
 when inoculation was made early. In the earlier stages of the 
 inflammation the bacilli anthracis almost completely filled the capil- 
 laries, much more so than usual, but the poison did not leave the 
 blood-vessels. Heubner has never succeeded in convincing himself 
 of these bacilli ever showing themselves outside the capillaries. 
 
 After having found that the infectious agent in the presence of 
 the locally diseased mucous membrane accumulates in the enlarged 
 blood-vessels, instead of taking the anthrax poison, diphtheritic 
 masses were now inoculate'd just in the same manner as had been 
 done by Oertel. 
 
 A portion of the slime, rich in bacilli and micrococci, from the 
 tonsil of a diphtheritic patient, was taken and introduced into an 
 animal which had already been rendered locally diphtheritic. This 
 case showed very plainly that there is no doubt of an acute infectious 
 disease being produced in an animal inoculated with such materi- 
 al. The disease is characterized by an enlargement of the spleen, 
 haemorrhages on serous membranes, and death ensues in from 
 
56 EXPERIMENTAL DIPHTHERIA. 
 
 two-and-one-half to three days. Short bacilli were seen filling the 
 diseased blood capillaries, especially in those parts in which the 
 diphtheria had not yet induced death of tissue. 
 
 It became evident that these bacilli really represented the poison 
 which had caused the acute infectious disease, from the fact that por- 
 tions of the membrane thus rendered diphtheritic, reinoculated into 
 other animals, regularly caused the disease through many generations. 
 
 The second form of diphtheria had thus been produced, which 
 taught us that — given a local disease — the poison causing the acute 
 general infectious disease, accumulated in the locality which had, 
 primarily, been rendered diphtheritic. Why not, then, take it as 
 proven, that these bacilli were really the diphtheritic poison. 
 
 Heubner does not think that the evidence upon which to base 
 such a belief is as yet sufficiently strong, and in this regard differs 
 from the views advanced by Klebs, for the following reasons: If 
 these micrococci or bacilli be the diphtheritic poison, then it would 
 follow that in at least those cases of diphtheria in which death is. 
 caused, not by the local disease, but by the acute genera. 1 infectious 
 disease, these bacilli must* needs have been present, . ch pres- 
 ence being liable of proof with the same methods in the 'ocally dis- 
 eased blood-vessels as in the artificially produced diphtheria. 
 
 t 
 Entire series of sections of uvulas have been made, and while micro- 
 cocci could be plainly recognized on the surface, none were seen 
 within the lumen of the otherwise enlarged blood-vessels, and there- 
 upon the conclusion that the organized materies morbi of diph- 
 theria has, up to date, not yet been found. Nor does H. con- 
 sider it proven, that the diseased mucous surface is the locality 
 where the diphtheritic poison first establishes itself and that 
 thence it finds its way into the general economy. . _j a further 
 reason for his views he adduces the fact that no cas: is hitherto 
 known of an infectious poison penetrating through healthy epithe- 
 lium. The attempt to introduce infectious material through the 
 mucous surface of the vagina of the rabbit has nev r succeeded. 
 In all our infectious diseases depending on bacteria, the latter enter 
 the economy either through inhalation, or food, or inoculation, and 
 not through healthy epithelium. Then, with regard to the relation 
 of the local process of diphtheria to the fever, we find that the 
 highest fever is always found on the first day of the disease, and 
 regardless of the spread of the local trouble. Such is certainly not 
 
EXPERIMENTAL DIPHTHERIA. 57 
 
 the case in an infectious disease depending on local infection. In 
 erysipelas, for instance, we have a new rise in temperature for every 
 new spread of the local disease. 
 
 As a third reason he gives one based on therapeutical results. 
 In his opinion the local treatment, beyond a certain amount of 
 cleanliness, amounts to nothing, and that it is through internal treat- 
 ment that we must try to antagonize the poison. 
 
 In this respect Heubner agrees with the great majority of prac- 
 tical American physicians, as will be readily seen by reference to the 
 " Collective Investigation of Diphtheria as Conducted by the Thera- 
 peutic Gazette, Detroit, Mich." Out of 92 physicians who gave a 
 positive opinion with regard to the treatment of the disease, only 12 
 advocated or laid more stress on local treatment than on constitu- 
 tional treatment; 29 declared themselves decidedly for constitutional 
 treatment. alone and 51 for both local and constitutional, laying, how- 
 ever, the greatest weight on the constitutional part of the treatment. 
 Jurgensen believes in a very thorough local disinfection 
 in all cases of diphtheria, but not with caustics ; he is of the opinion 
 that a gc ral disinfection of the body is not practicable and, that 
 the only tlfing to be done in the way of general treatment is, to 
 supply nourishment in abundance. 
 
 Rossbach cannot agree with Heubner with regard to the 
 penetration of micro-organisms through the mucous membrane of 
 the throat. The tonsils, he argues, are organs through which con- 
 stantly large numbers of white blood corpuscles emigrate, and there- 
 fore he thinks that wherever a white blood corpuscle can come out, 
 a bacillus may get in. He tells of cases of diphtheria in which the 
 tonsils had previously been removed and in which the places 
 formerly oc pied by the tonsils remained free from the diphtheritic 
 invasion. He recommends papayotin for the purpose of digesting 
 the false membrane in diphtheria, but at the same time calls at- 
 tention to the fact that there is papayotin in the market which has 
 lost all digestive powers and is useless, and that, therefore, care must 
 be taken to gee a good preparation. 
 
 Leube s .lotwithstanding the general prejudice against the 
 application of any caustics to the throat in cases of diphtheria, ad- 
 mits having obtained excellent results from an application of a 
 solution consisting of carbolic acid and alcohol in equal proportions. 
 He says the application, in order to prove effectual, must be made 
 
58 EXPERIMENTAL DIPHTHERIA. 
 
 early and thoroughly. Besides trying this on a great many other 
 patients, L. has had the opportunity of trying it on himself twice and 
 always with great success. Once he was taken with the disease and his 
 tonsils were completely covered with the exudation within a few hours. 
 One single but thorough application of the solution of carbolic acid 
 and alcohol was made. Towards evening the fever went down and on 
 the next morning the exudation in the throat had entirely disappeared. 
 In the second case occurring on his own person, three applications 
 became necessary, but that was the highest number of applications 
 he ever found it necessary to make. Leube is somewhat inclined to 
 believe in the chemical nature of the diphtheritic poison, though he 
 is very guarded in how he expresses this belief. This view certainly 
 finds support in the fact that albuminuria, which is usually present 
 in diphtheria, is not directly caused by the presence of micro-organ- 
 isms within the kidney, and examination of the urine has never 
 resulted in the finding of bacilli or other micro-organisms in cases of 
 diphtheria. On the other hand, the bacillus tuberculosis has been 
 found in the urine in cases in which the disease had made consider-' 
 able progress in the kidney. • 
 
 Edlefsen states that his experience had always led him to 
 believe that scarlatinal diphtheria was something separate and dis- 
 tinct, and that this kind of diphtheria never extends to the throat 
 and trachea. He admits, however, that a complication with true 
 diphtheria may obtain in scarlatina. Concerning the cause of death 
 in diphtheria directly traceable to disease of the heart, he remarks that 
 this heart complication is not always due to a parenchymatous, fatty 
 or granular degeneration of the heart-muscle, but sometimes, also, to 
 a paralysis of the nervous apparatus, more especially in the heart 
 ganglia. He does not think that the trouble in these cases is due to 
 paralysis of the vagus, since the characteristic point is a slowing of 
 the pulse-rate, which contrasts very markedly with the acceleration 
 we meet with in muscular degeneration. 
 
 Lichtheim maintains that all those diseases which have been 
 produced by the inoculation with micro-organisms, taken from the 
 throat of diphtheritic patients, were not diphtheria and had nothing 
 to do with diphtheria; these micro-organisms were simply accidental 
 parasites, and the diphtheritic virus remained still to be discovered.