LETTER 
 
 TO THE 
 
 REV, JOHN BACHMAN, D, D,, 
 
 ON THE QUESTION OK 
 
 HYBR1DITY IN ANIMALS. 
 
 CONSIDERED IN REFERENCE TO 
 
 THE UNITY OF THE HUMAN SPECIES; 
 
 BY SAMUEL GEORGE MORTON, M. D. 
 
 Pennsylvania and Edinburgh. 
 
 f Californi 
 
 Regional 
 
 Facility 
 
 CHARLESTON, S. C.: 
 
 STEAM-POWER PRESS OF WALKER <fe JAMES, 
 
 No. 101 East-Bay, 
 
 1850.
 
 UCSB LIBRARY 
 
 LETTER 
 
 TO THE 
 
 REV. JOHN BACHMAN, D. D., 
 
 ON THE QUESTION OF 
 
 HYBR1DITY IN ANIMALS, 
 
 CONSroERED IN REFERENCE TO 
 
 THE UNITY OF THE HUMAN SPECKS. 
 
 BY SAMUEL GEORGE MORTON, M. D. 
 
 Pennsylvania and Edinburgh. 
 
 CHARLESTON, S. C.: 
 
 STEAM-POWER PRESS OF "WALKER & JAMES, 
 No. 101 East-Bay, 
 
 1850.
 
 LETTER TO DR, BACHMAN, 
 
 PHILADELPHIA, MARCH 30, 1850. 
 
 Dear Sir : Having read your review of my " Essay on Hybridity," 
 in the last number of this Journal, I feel called upon to offer some ob- 
 servations in reply ; and I take this step with the more pleasure, because 
 it does not appear to me that you have refuted any one of my six pro- 
 positions. On the contrary, the perusal of your criticism only confirms 
 me in them all. 
 
 Permit me to commence, by saying that I fully reciprocate the kind 
 sentiments you have expressed with respect to myself; for no difference 
 of opinion can diminish my esteem for you as a man, or lessen my admi- 
 ration for one who, by common consent, stands in the front rank of Ame- 
 rican Zoology. Yet, I cannot suppress my surprise that you should 
 reject all my authorities, because they conflict with your own views ; for 
 if such men as Buffon, Temminck, Hamilton Smith, and others whom I 
 have cited, are not to be believed in questions of science, then I confess 
 we may as well reject all human testimony at once, and rely, for the 
 future, solely on our own observation; which, like the others, and by the 
 same rule, will in turn be denied and discarded by those who follow us. 
 
 I cannot concur in yonr strictures on Hamilton Smith. I see in him 
 a man who has grown gray in the pursuit of Science. He has attained 
 its honors, and is deserving of the gratitude of the present age and of 
 posterity. In fact, in the philosophy of Natural History, he appears to 
 me to be a century in advance of most of his contemporaries. If one 
 who has accomplished so much has committed some errors of judgment, 
 let us be gentle in our censure. Let us review our own works and see if 
 we have done better. For my own part, I must confess to various errors 
 both of fact and opinion ; and these things have made me more circum- 
 spect in myself and more charitable to others. 
 1
 
 And here it is necessary for me to correct an impression of yours with 
 respect to a passage of De Azzara, quoted in my essay. You have not 
 been able to find it in the French edition ; but in Hunter's translation, 
 London, 1838, page 173, after some preliminary observations, you will 
 see the following paragraph, which is the one from which mine was 
 abridged : 
 
 " I have heard that on the plains, my black cat, the yayuarundi and 
 the eyra, all unite with the domestic cat. From this connection crossed 
 breeds will necessarily result ; and if, in the course of time, these coun- 
 tries should become populous, and these wild-cats, as would infallibly be 
 the case, should be extirpated, could it then, with any propriety, be 
 affirmed that all the domestic races proceeded from one species which 
 had remained wild, as the naturalists of the old world maintain ? M 
 
 I cite this passage entire for several reasons : 1st. To show that it 
 does exist in De Azzara ; 2d. Because it proves him an advocate for the 
 principle of fertile hybridity ; and 3d. Because it appears that I had 
 attached too much importance to the statement, inasmuch as the great 
 naturalist does not record the facts from his personal knowledge, but 
 merely on the information of others, who may possibly have been mis- 
 taken. 
 
 I consider my statement respecting hybrids of the sheep and goat, to 
 be a perfectly authenticated fact ; nor do I think you justified in the fol- 
 lowing expressions : '' The Journal des Savants, in which these crudities 
 are published, has not reache 1 us ; and as the author states that in or- 
 der to keep up the breed they must resort to the original stock, and 
 thus nature prevents the creation of a new race, it is unnecessary for us 
 to hunt up and comment on the authority." In what respect the facts 
 of M. Chevreul are crudities, I cannot see ; and if you were to hun t, up 
 the authority, I think you would find the statement precisely as I have 
 given it. I am the more astonished at your summary disposal of M, 
 Chevreul's facts, inasmuch as similar statements have been on record for 
 a century, and are fully admitted by Buffon ; and if you will turn to 
 Cuvier's description of the genius Ovis, you will find him remark, in 
 reference to the sheep and the goat, " the two produce a prolific off- 
 spring ;" and for this very reason, as would appear, he considers them 
 to be but slightly entitled to a generic separation. Did it never occur 
 to you, when you journeyed ten miles of your road to see " a large 
 ram with a hairy fleece and rather strait horns," that the animal was a 
 cross-breed of the very kind of which we have just spoken ? 
 
 There are some questions in science that must always remain a mat-
 
 ter of opinion; and among these is the origin of the domestic sheep ; 
 some referring all its varieties to the Aryali, (Ovis ammon,) others to 
 the Moufflon, (Ovis musmon ;) and the great Cuvier seems not to 
 have made up his opinion on this point ; for he says, " it is supposed 
 that from the Moufflon, or from the Argali, are derived the innumerable 
 races of our woolly animals." You remark, that " it remains for our 
 opponents to prove that our different varieties of sheep have been de- 
 rived from commingled species." Permit me to say that I believe it 
 equally difficult to prove the converse of this proposition ; for even those 
 naturalists who consider them all as the descendants of one species, re- 
 fer us to at least two distinct species for the origin of the race. 
 
 1 stand corrected with respect to the Capra cegagrus, which is by 
 general consent admitted to be the source of the common goat ; but 
 look into Cuvier, genus CAPRA, and you will there observe that he de- 
 cribes two very distinct species, the C. ibex and C. caucasica ; and he 
 concludes his remarks in these words : " The two species mix with the 
 domestic goat." He further states, in some preceding remarks, that 
 " there is a race of goats in upper Egypt, with short hair, convex chauf- 
 rin, and projecting lower jaw, which possibly is hybrid." In these ex- 
 amples Cuvier sustains Hamilton Smith. 
 
 Your remarks upon the hybrid between the Finland ram and Sar- 
 dinian doe, are of the dogmatical class ; and so also those respecting 
 the Camel*. The best Zoologists, with Cuvier at the head of them, di- 
 vide the camels into two sixties. This authority is sufficient for me, and 
 [ have always adopted it. Btiffou and others, you remark, have re- 
 garded them " only as varieties of the same species." I will give you 
 the reason of Buffon's opinion. He maintained the postulate of Ray, 
 " any two animals that can procreate together, and whose issue can 
 procreate, are specifically the same." Now, since the two camels produce, 
 inter se, a mixed offspring, he for that reason and for that alone, referred 
 them to the same species. The following are his words, which I trans- 
 late as literally as possible : 
 
 " The two kinds of Camel produce together, and the individuals de- 
 rived from this cross possess more vigor than the original stocks, and are 
 consequently more highly valued than the others. These hybrids, the 
 issue of the dromedary and the camel, constitute a secondary race which 
 is equally prolific, (qui se multiplie pareillement) and mixes with the 
 primitive races."* 
 
 Buffou was a most industrious and at the same time a very cautious, 
 and I may add, conscientious collector of facts ; but like other men of 
 
 * Buffon, Hist Naturelle : ed Sonnini, T. xxix, v. 5, 8.
 
 genius, he sometimes erred in opinion for the sake of hypothesis ; and 
 the justice of this remark may be shown by a single example. The 
 great naturalist absolutely classed -all the ox-tribe into one species be- 
 cause they were capable of re-producing among themselves a hybrid 
 offspring thet could perpetuate itself by union with the parent stocks! 
 And in this category he includes the domestic cattle, the ox of Europe, that 
 of Asia and Africa, the Bison of America, the auroch and the zebu !* 
 So completely was Buffon blinded by this hypothesis, that it led him 
 into errors of judgment in which he is not sustained by a single zoolo- 
 gist of the present day. 
 
 In another place you take exception to my remark that the fecundity 
 of the progeny of the horse and the ass " depends much on tempera- 
 ture," and you add a doubt whether these phenomena occur more fre- 
 quently in hot than in cold climates. Mules have been most fertile in 
 St. Domingo, Spain, Italy and New Holland. " Ces faits, qui me para- 
 issent bien constate*s, nous demontrent que, dans les climats chauds, la 
 mule peut non settlement concevoir, mais perfection ner et porter a ter- 
 me son fruit."f 
 
 While on this subject I may add the remarkable fact, that in the city 
 of Valencia, in Spain, a horse and she mule produced colts on five dif- 
 ferent occasions ; and the same mule subsequently bore another colt by 
 another horse.J 
 
 I regret to observe that when'l quote Prof. Owen for the fact of a 
 mule between a bull and a sheep, you quote the adverse opinion of 
 that distingushed man on the question of fertile hybridity, just as if such 
 an opinion would do away with the fact which he had himself recorded. 
 In the passage quoted from Prof. Owen he observes that " the individ- 
 uals of different species do not voluntarily copulate." 
 
 This statement only goes to prove the correctness of the proverbial say- 
 ing that a man cannot be equally great in every thing; for while naturalists, 
 
 * Opus citat. Tome xxix, p. 120, 124, 137, 153. 
 
 f Buffon, ut supra T. xxii, p. 421. For the fact of the prolific character of the 
 mule in New Holland, see also Trans, of Entomolug Soc. of London, I, p. 267. 
 
 \ Buffon, op. citat. T. xxix, p. 577. 
 
 Dr. Shaw, in his travels Jn Algiers, states that he saw the hybrid offspring^ of 
 an ass and a cow. He describes it as a small animal, with the head and tail of 
 the cow, but with a solid foot like the ass, and destitute of horns. This cross is 
 called by the French jumar, and is said to have repeatedly occurred in Southern 
 France. Another hybrid bearing the same name is declared to have been more 
 than once derived from the bull and she ass. Sonini, in Buffon, xxii. p. 449.
 
 by common consent, admit Professor Owen to be the lineal heir of the 
 mantle of Cuvier, it is also manifest that some persons have enquired 
 into the present subject more deeply than that eminent naturalist has^ 
 done. Independently of the evidence derived from the family of birds - 
 (which will be stated hereafter) that difterent species of animals do vol- 
 untarily unite even in the wild state, I will now !_m<- some examples from 
 the mammiferous class. 
 
 Sir W. Jardine, speaking of the domestic cat, has the following para- jt 
 graph : 
 
 ,JU 
 
 "We have no doubt that since its (tin- K^\ptian calif" introduction 
 into Great Britain and more particularly to the north of Scotland, there 
 has been occasional crossing with our own native ^pecu-s, and that the 
 results of these crosses have been kept in our houses. We have seen 
 many cats closely resembling the wild cat, and one or two that were 
 very tame, which could scarcely be distinguished from it,"* 
 
 Bewick also observes, that the wild eat of Europe (Felis cattus) is said 
 not unfrequently to cross with the common cat. which last rears a family; 
 and he adds, that this explains the not unusual resemblance of the tame 
 to the wild species.f Xor does it seem that these hybrids are any 
 less prolific than the parent stocks. 
 
 Cuvier himself suggests that the Bos frontalis of Lambert, a domes- 
 tic breed of cattle in the north-west of India, may be descended from a 
 union of the buffalo (Bos bubalus) the indigenus animal of that coun- 
 try, and the common species.J Thus Cuvier suspects the Bos fronta 
 now so numerous in Hindostan, to be a prolific hybrid ; and k'may 
 relevantly added that the same great naturalist records 
 that the singular varieties of the domestic pigeon an- -l.'ri\ 
 from one species, the columba livia, but that theyvMBg^ 
 union of that species with another but unknown "' r 3|9H 
 
 Buffon states that in Champagne, in the year 1^9^ e%n"t young 
 wolves were found, which were satisfactorily traced to the parentage of a 
 common dog and she wolf. They were all killed wild in the forest, 
 while young ; thus preventing any chance of their re-producing among 
 themselves. A wild cross was also found near Metz, in the year 1784 ; 
 and another in Normandy ten years earlier. 
 
 The ancients averred, without hesitation, that the dog, in some coun- 
 
 * Naturalist's Library, voL ii, p. 243. Felinae. 
 
 f Quadrupeds, p. 228. 
 
 \ Animal Kingdom, I. p. 201. 
 
 Buffon op. citat. xxxii., p. 231, 329, 333.
 
 8 
 
 tries and under some circumstances, was accustomed to breed with the 
 wolf and fox. "In Cyrenensi agro," says Aristotle, "lupi cum canibus 
 coeunt ; et laconici canes ex vulpe et cane generantur."* 
 
 These and many other examples quoted by Buffon and Sonnini, estab- 
 lish two propositions : 1st. That certain different species of animals 
 copulate voluntarily with each other ; and 2d. That new races have 
 been formed by the union of such species. 
 
 Some remarkable confirmations of these principles will be adduced 
 hereafter, when adverting to the bird-hybrids. 
 
 In the next place, I observe with surprise that your review of my essay 
 extends no farther than the marnmiferous class. Why were not the 
 birds examined also ? For here the evidence is even stronger, and I pre- 
 sume will not and cannot be set aside by any argument whatever. 
 
 You admit that " in two or three species a progeny has been pro- 
 duced, where the hybrids were fertile for a few generations, and then 
 became sterile." And at the close of your inquiry you exclaim of your 
 opponents " have they gone farther than merely to indulge in specula- 
 tion and conjectures, and in endeavoring to throw the shadows of doubt 
 on opinions long entertained by the world of naturalists ?" These re- 
 marks appear to me to be incompatible with each other ; and in order 
 to prov e it, and at the same time to bring forward some facts obtained 
 since my essay was published, I propose, in the next place, to state and 
 defend each of my six propositions as originally announced. 
 
 1. A latent power of hybridity exists in many animals in the wild 
 state, in which state, also, hybrids are sometimes produced. 
 
 By a latent power of hybridity in the wild state, I mean a power that 
 seems only to be evolved by domestication. For example, the several 
 species of Hoccos, (genus Crax) unite freely with each other in Holland ; 
 and yet there is no proof that they do so in their native forests of South 
 America. And I believe the same remark holds good with respect to 
 the common fowl ; yet Temminck has shown that no less than five spe- 
 cies of this genus (Gallus] produce freely with each other in the domes- 
 ticated state.f 
 
 That some animals, in a wild state, intermix with each other and pro- 
 duce a hybrid offspring, is now admitted by every candid observer. I 
 have heretofore recorded abundant evidence under this head, nor does it 
 
 * De Animalibus, lib. viii., 28. 
 
 f Gallus bankiva, G. giganteus, G. morio, G. crispus and G. furcatus. He adds 
 that G. lanatus produces with the otherB a sterile progeny. Pigeons et Gallinaces, 
 II., p. 275, 276.
 
 9 
 
 seem necessary to add to it. Some further examples, however, may not 
 be inappropriate on the present occasion. 
 
 You yourself inform me that you have in your possession the mounted 
 skins of two hybrid hares, between the American gray rabbit, Lepus syl- 
 vaticus, and the marsh hare, Lepus palustris. In an obliging letter to 
 me, you make the following remark : " At the time of finding these ani- 
 mals, I supposed they would prove to belong to an undescribed species ; 
 but I am now quite sure that they are the hybrid product of the above 
 named hares." I believe this is one of the first fully authenticated ex- 
 amples of hybridity in the wild state that has been noticed on our 
 continent, and I have great pleasure in referring to you for the fact. 
 
 The species of Birds are so vastly more numerous than those of 
 quadrupeds, that it is among these that we should expect a correspond- 
 ing frequency of hybrid productions. In addition to the extended series 
 embraced in my Essay, I now submit the following additional examples 
 all of which occur in the wild state. 
 
 The Tetrao urogallus, or wood-grouse, breeds with the black-grouse, 
 
 Tetrix, and the hybrids are called in Sweden Racklehanen. It is, 
 indeed, so common in that country and in Norway that among a single 
 lot of grouse brought thence to London for sale, Mr. Yarrell detected 
 no less than seven of these hybrids. It was long regarded by natural- 
 ists as a distinct species under the name of Tetrao medius* but it is 
 now pretty generally admitted to be a mule bird. I have examined 
 two of them in the Wilson Collection, in the Academy of Natural Sci- 
 ences of Philadelphia ; and similar examples are common in all ornitho- 
 logical cabinets. 
 
 The celebrated Temminck, however, considers the Tetrao medius a 
 true species independently of its exterior characteristics : first, because 
 it is produced in the wild state, and secondly, because the forests of 
 northern Europe, in which it is found, are equally peopled by both the 
 species of which this bird is the supposed hybrid. But these objections 
 are no longer availing ; for the concurrent testimony of all the later 
 ornithologists proves this bird to be a mixture of two species, and con- 
 firms the opinion of Linnoeus, published a century ago and expressed 
 in his name of Tetrao hybridus. It would be difficult to prove that 
 these cross breeds are prolific inter se, but that they are so with the 
 parent stock may be safely inferred from the many grades of interme- 
 diate plumage ; and it is a curious fact that Klein, in his ova avium, 
 
 * Pigeons et Gallinaces, iii., 131.
 
 10 
 
 (Leipsic, 1766,) has figured what is supposed to be the egg of this bird r 
 because its markings are made up of those of both original species. 
 
 The following species also produce hybrids in the wild state: the 
 Black grouse, Tetrao tetrix, with the English pheasant,* the T. tetrix 
 with the T. subalpina,\ and the T. urogallus with the T. scoticus. 
 
 The hooded crow pairs and produces with the carrion crow,^ and the 
 same is true of the two species of circus, commonly called harriers. 
 
 So much for my first proposition. I now proceed to the second : 
 
 2. Hybridity not only exists among different species, but among dif. 
 ferent genera, and the cross-breeds have been prolific in both cases. 
 
 In support of the first part of this proposition, that animals of dif- 
 ferent species are capable of producing prolific hybrids, I shall now add 
 the celebrated experiments of Buffon, which were omitted from my 
 Essay for the simple reason that I could not, at the time of writing it, 
 obtain an authentic account of them. 
 
 1. Buffon brought together a cur-dog and a she- wolf, and the result 
 of this union was a litter of four pups, two male and two female. No 
 difficulty occurred in procuring this cross. 
 
 2. A male and female of the first generation were coupled, and four 
 pups were born, of which two lived to maturity a male and a female. 
 
 3. This second generation crossed, and produced a generation of seven 
 pups. 
 
 4. A female of the third generation was crossed by her sire, and four 
 pups were produced, of which a male and a female lived.)] 
 
 With these facts the history ceases ; not from any difficulty, it would 
 seem, between the animals themselves, but on account of the constant 
 care requisite to prevent the union of the common dog with these 
 hybrids, so that the experiment became fatiguing after its continuance 
 for several years, and it was discontinued on that account. It thus 
 appears that the dog and wolf bred inter se through three generations ; 
 nor was either one of the parent animals permitted to unite with the 
 pure hybrid until the fourth generation. 
 
 The young animals, says Buffon, both in number and strength of 
 constitution, compared well with other dogs for those that did not 
 attain to adult age were mostly killed by some accident, and not by 
 
 * YarrelL British Birds, pp. 307 312. 
 
 | Nilsson. Ornithologia Suecica, p. 303. 
 
 | Proceedings of the Zoological Society of London, 1836. 
 
 Yarrell. Ut Supra, iL, p. 87. 
 
 | Buffon. Ut supra, xxii, p. 257-320.
 
 11 
 
 disease. Nor is there any circumstance connected with these experi- 
 ments to cause a doubt that, had it been continued with equal care, and 
 on an enlarged scale, these hybrids would have multiplied to an indefi- 
 nite extent. 
 
 But does it not occur to you that this experiment, with all its pre- 
 cautionary attendants, was a faulty one ? And why ? Because it was 
 on too small a scale to afford a fair chance of complete success. We 
 may readily conceive that the result would have been far more satisfac- 
 tory, if the offspring of several couples of the dog and wolf had been 
 obtained and allowed to mix with each other. 
 
 How comes it, then, you will inquire, that there is no new race de- 
 rived from the dog and wolf, or the dog and fox ? I answer, because 
 they are not wanted. Wolves and foxes are destroyed without mercy ; 
 and such also has been the fate, as we have already shown, of those 
 animals which have accidentally resulted from their mixture with the 
 common dog. The experiment has never been tried except from mere 
 curiosity ; and its success has been complete when we consider the dis- 
 advantages by which it was surrounded ; for the mere process of breed- 
 ing in and in, from the progeny of a single pair of any animal, has by 
 uniform experience tended to deterioration and extinction. On this 
 point I purpose to make some remarks in the sequel. 
 
 I presume that the facts just mentioned, together with those cited in 
 my Essay from both quadrupeds and birds, are sufficient to establish, be- 
 yond cavil, the simple fact that animals of different species are capable 
 of producing a fertile hybrid offspring. 
 
 Now for the second part of my first ' proposition that animals be- 
 longing to different genera do also unite with like results. I consider 
 myself sufficiently sustained in this instance by the facts already 
 adduced with respect to the sheep and the goat. I have the testimony 
 of Buffbn, Cuvier and Chevreul that the progeny is fertile ; nor does 
 any one of these authorities state that the hybrids will not reproduce 
 inter se ; and M. Chevreul notices the necessity of admitting one of 
 the parent animals merely for the purpose of obtaining a finer fleece. 
 
 I do not abandon the asserted fertile hybrids between the Marten, 
 Mustela martes, and the common cat. I am willing with yourself to 
 receive the statement with caution ; but the details are too explicit to 
 permit us to deny them without further investigation. 
 
 The only example of this class of hybrids that has occurred in my 
 readings since my Essay was published, is that of the Thrush, (Merula 
 vulgaris) and Blackbird, (Turdus merula,) which have been observed to
 
 12 
 
 pair in England, and to produce strongly marked hybrids during two 
 successive years. * 
 
 3. Domestication does not cause this faculty, but merely evolves it. 
 This is a self-evident proposition, as the preceding facts amply testify ; 
 
 and my reasons for bringing it forward were to show, that what Tem- 
 minck and Prichard have termed the natural repugnance of different 
 species to intermingle, has many exceptions ; and further, that Dr. 
 Prichard is not correct when he assumes the law of the case to be that 
 this repugnance is " overcome in the state of domestication, in which the 
 natural propensities cease, in a great measure, to direct their actions." 
 This is one of the several postulates respecting hybridity, that must 
 now be abandoned; for the evidence I have given is conclusive 
 against it. 
 
 4. The capacity for fertile hybridity, cceteris paribus, exists in ani- 
 mals in proportion to their aptitude for domesticity and cultivation. 
 
 This proposition, like the preceding one, is an obvious truth, requiring 
 no further elucidation ; and man, in the language of Blumenbach, being 
 the most perfect of animals, this faculty is perhaps the most perfectly 
 evolved in him. I reserve some remarks on this subject for the sequel. 
 
 5. Since various Afferent species of animals are capable of pro- 
 ducing toyether a prolific hybrid offspring, hybridity ceases to be a test 
 of specific affiliation. 
 
 This proposition is certainly borne out by the facts above stated, and 
 by those of my Essay. I do not deny that the aeneral law of Nature is 
 opposed to the remoter degrees of hybridity ; but the exceptions are so 
 remarkable, even with regard 'to these, that they invalidate the rule. 
 
 6. Consequently, the mere fact that the several races of Mankind, 
 produce with each other a more or less fertile progeny, constitutes, in 
 itself, no proof of the unity of the human species. 
 
 Your strictures do not show me the necessity of relinquishing, or even 
 of modifying, any one of these propositions ; but there are some differ- 
 ences of opinion between us, and I next proceed, as briefly as possible, 
 to examine them ; not with a view to criticise the belief of others, but 
 merely to state my own convictions on a subject which has occupied no 
 small share of inquiry and reflection. 
 
 Hybridity is divisible into four degrees or grades, which may be ex- 
 plained in the following manner. 
 
 The first degree is that in which the hybrids never re-produce ; in 
 
 * Barry, in Mag. of Nat. Hist. voL viii., quoted by Mr. Yarrell.
 
 13 
 
 other words, the mixed progeny begins and ends with the first cross. A 
 large proportion of the known mixed breeds belong to this class, and 
 they embrace animals of entirely different genera. Several of them 
 have been indicated in the foregoing pages ; and for some curious infor- 
 mation on this head, the reader is referred to the researches of M. Selys- 
 Longchamps, who has recorded authenticated examples of hybrids of 
 twenty-four crosses between different species of swan, goose and duck, 
 all of which proved sterile excepting those between Anser cygnoides and 
 A. cinereus, Cygnus olor and C. mutabilis, and Anas bo&chas and A. 
 acuta* Indeed, nearly all domesticated birds, however different in 
 generic relations, are capable of producing a mule offspring by mingling 
 with each other. 
 
 The second degree of hybridity is that in which the hybrids, whether 
 generic or specific, are incapable of re-producing inter se, but multiply, 
 to any extent, by uniting the hybrid with a full-blood animal of either 
 of the parent stocks. The American bison, Bos Americanus, re-pro" 
 duces in this way with the common breed of cattle, as you have fully 
 shown ; and Kalni, the Swedish traveller, states that these animals 
 mixed with each other independently of the influence of domestication. 
 
 The same remark is true with respect to all the known species of the 
 genus Bos, whether in Asia, Africa or America ; and this second remove 
 from the original stock, is capable, so far as my knowledge goes, of 
 breeding inter se and without limit, provided a sufficient number of hy- 
 brids of the same grade are brought together, to prevent the stock from 
 being destroyed by too close inter-breeding. Races might be formed 
 and perpetuated in this way, were they worth the trouble ; but this not 
 being the case, the hybrids are permitted to breed with the parent 
 stocks, in which they soon become lost, on account of the great prepon- 
 derance of individuals of those stocks. The several species of goats, as 
 we have seen, belong to this class of hybrid-forming animals. So also 
 various other animals capable of domestication, as I have already pointed 
 out, especially in my Essay. I will now only add two other examples. 
 Two species of ferrets, Mustelafuro and M. putorius, are often crossed 
 in England, in order to obtain improved breeds ;f and two doves, the 
 common turtle, Columba turtur, and the collared turtle, (7. risoria, 
 though specifically and remarkably different from each other, unite to- 
 gether, and, according to Beckstein, produce fruitful hybrids. J 
 
 * Hybrides des Anatidees. Bulletin de 1'Acad. Roy. de Bruxellos. T. XII. 
 f Bewick. Quadrupeds, p. 252. 
 \ Singing Birds, p. 287.
 
 14 
 
 The third degree of hybridity is that in which animals of unquestion- 
 ably distinct species, unite and produce a progeny that is prolific inter 
 se. Such is the case with respect to the dog and wolf in the experi- 
 ments of Buffon ; and such also, I believe, was the result in the dog and 
 fox, as coupled by John Hunter, and in the dog and jackal, as obtained 
 by others. Several species of birds further illustrate this proposition ; 
 although the examples are very limited, and, as we have heretofore ad- 
 mitted, contrary to the general law of nature. If Buffon's statement, 
 therefore, is true, (and no one has ever questioned it, and it appears to 
 have been accomplished to his own surprise and even to his regret) then 
 his aphorism is not true, viz : that all animals capable of producing an 
 offspring which can again re-produce among themselves, are necessarily 
 of the same species. 
 
 " We may take the law of sterility in the commixture of different 
 species," observes Hamilton Smith, " to have its limits where the forms 
 cease to be sufficiently homogeneous ; a law unquestionably ordained for 
 the wisest purposes, but marked by exceptional modifications for pur- 
 poses not less beneficent."* 
 
 This may be received as an axiom in science ; and I further believe, 
 with Azzara,f that many species or varieties of animals are so entirely 
 homogeneous in their organization, that, although distinct in their ori- 
 gin, they have been endowed with a faculty of fertile intermixture, which 
 is rapidly and almost interminably evolved by domestication ; whence 
 arises 
 
 The fourth degree of hybridity. This phenomenon is characteristic of 
 man, the ox tribe, horses, sheep, goats, dogs, etc. ; thus embracing the 
 head of the zoological series, and those animals most essential to his 
 wants and his happiness. 
 
 I am well aware that, to use your own phrase, you will " join issue" 
 with me on these points. They are matters of opinion ; you have yours, 
 I have mine. I believe in a plurality of origin for the human species ; 
 that they were created, not in one pair, but in many pairs ; and that 
 they were adapted, from the beginning, to those varied circumstances of 
 climate and locality which, while congenial to some, are destructive to 
 others. Hence the differences in their physical characteristics, and in 
 their mental and moral endowments. It would be impossible in the 
 limited space allotted to this communication, to examine and discuss a 
 question involving so many facts, both direct and collateral ; but I must 
 be permitted briefly to " define my position" in reference to it. 
 
 I commenced the study of Ethnology about twenty years since ; and 
 
 * Equidie, p. 'JO. f Quadrupeds, I., p. 95.
 
 among the first aphorisms taught me by all the books to which I then 
 had access, was this that all mankind were derived from a single pair ; 
 and that the diversities now so remarkable, originated solely from the 
 operations of climate, locality, food and other physical agents. In other 
 words, that man was created a perfect and beautiful being in the first in- 
 stance, and that chance, chance alone has caused all the physical disparity 
 among men, from the noblest Caucasian form to the most degraded Aus- 
 tralian and Hottentot. 
 
 I approached the subject as one of great difficulty and delicacy ; and 
 my first convictions were, that these diversities are not acquired, but have 
 existed ab origine. Such is the opinion expressed in my Crania Ameri- 
 cana ; but at that period, (twelve years ago) I had not investigated scrip- 
 tural Ethnology, and was content to suppose that the distinctive charac- 
 teristics of the several races had been marked upon the immediate fami- 
 ly of Adam. 
 
 Further investigation, however, in connection with zoological science, 
 has led me to take a wider view of this question, of which an outline is 
 given above ; but I never fully adopted and announced this conviction 
 until I felt fully satisfied that it was in harmony with the Sacred Text, 
 and reconcileable with the sublime teachings of Genesis.* 
 
 Thus in common with many other inquirers, I regard the first chapter 
 of that book to give what may be called a generic or general account of 
 the creation of Man ; and this is expressed in precisely the same terms 
 which are iised in reference to the other classes of animals, " male and 
 female created he them," without reference to the number or locality. 
 If we next examine the second chapter of Genesis we find another ac- 
 count of the creation of man in and for a particular region ; and it 
 further appears that even the vegetable kingdom was at the same time 
 provided with additional elements, in order to render this locality yet 
 more emphatically a paradise for the Adamic race, and not a collective 
 centre for the whole human family. 
 
 To show that the evidence of facts tends strongly to this view of the 
 case, and to prove that it is not at variance with the record of the Pen- 
 tateuch, I beg leave to quote a short passage from the writings of a cler- 
 gyman remarkable alike for his erudition, his piety and his clear per- 
 ception of the relative position of science and revealed religion. 
 
 "If the two first inhabitants of Eden were the progenitors, not of all 
 human beings, but only of the races, whence sprung the Hebrew family, 
 still it would remain the fact, that all were formed by the immediate 
 
 * Amer. Journal of Science and the Arts, 1847.
 
 16 
 
 power of God, and all their circumstances, stated or implied in the 
 Scriptures, would remain the same as to moral and practical purposes. 
 
 " Some difficulties in the Scripture history would be taken away 
 such as the sons of Adam obtaining wives who were their own sisters ; 
 Cain's acquiring instruments of husbandry, which must have been supplied 
 by miracle immediately from heaven, upon the usual supposition ; his 
 apprehensions of summary punishment ; his fleeing into another region, 
 of which Joseph us so understands the text as to affirm that Cain ob- 
 tained confederates and became a plunderer and a robber, implying the 
 existence of a population beyond his own family ; and his building a 
 ' city,' a considerable collection of habitations. 
 
 "Thus, if contrary to all reasonable probability, this great question 
 should ever be determined in the way opposite to what we now think 
 the verdict of truth, the highest interests of man will not be affected."* 
 
 Thus we see that this eminent biblical scholar, although himself dis- 
 posed to adopt the " Unity doctrine," finds no difficulty in the converse 
 of it; which last, I think, is fully sustained by a critical examination of 
 the other sections of the zoological series. But circumstances preclude 
 the expression, in this place, of the facts and arguments of the case, 
 which I reserve for another occasion. Thus much, however, seems 
 necessary to be said, because mankind, both naturalists and others, have 
 kept aloof from Ethnology, in the fear that its study would bring them 
 into collision with the Mosaic record. 
 
 A few words on another point. Many zoologists insist on the origin 
 of all animals from a single pair of each species; so that all the dogs, 
 for example, with their many and remarkable varieties, must have been 
 derived from one male and one female, while chance or accident are 
 appealed to in explanation of their diversities of form, color and instinct. 
 
 Now I can find nothing in the account of creation, as contained in 
 the first chapter of Genesis, to sustain a doctrine of this kind ; and if it 
 be said that they entered the ark in pairs, I have two replies to make : 
 
 1st. That geology proves the Deluge to have been a local phenome- 
 non; and this is the almost unanimous verdict of those persons who have 
 studied that cataclysm in connection with the fossiliferous strata ; and 
 I here again refer to the work of Dr. J. Pye Smith, for a full exposition 
 of the evidence. 
 
 * Rev. J. Pye Smith, D.D., L.L.D. Relation between the Holy Scriptures and 
 Geology, p. 398-400. 3d editioa 
 
 I regard this among the most instructive volumes that has issued from the press 
 since the revival of letters, and for this reason that it constitutes a link between 
 religion and natural science studies which have hitherto been as isolated as if 
 they were incompatible with each other. Mr. Robert E. Peterson, of Philadelphia, 
 has the work in press, and will shortly publish it in a style not inferior to the Eng- 
 lish edition.
 
 17 
 
 2d. Some animals are said to have been received into the ark by 
 pairs, others by sevens, and among the latter were all birds and all clean 
 beasts. Did it never occur to you that, with this range between two 
 and seven, the text might be safely interpreted at least two ? Even if 
 we suppose, (what, however, is not necessary to a proper interpretation 
 of Genesis,) that no animals survived the Deluge but those received into 
 the Ark, we may reasonably infer that all varieties of domestic animals, 
 even those not strictly clean, would have been preserved on account of 
 their usefulness to man ? Buffon describes, if I mistake not, thirty differ- 
 ent varieties of dogs, (many of which may be regarded as true species,*) 
 and some of these are proved by Egyptian monuments to be as old as 
 the period ascribed to the Deluge by the Hebrew chronology. Why 
 were not these forms in part, at least, primeval ? Again, you will ob- 
 serve, on reference to Pye Smith's researches, that there is great proba- 
 bility that the Ark contained few or no animals but those capable of 
 domestication. 
 
 With respect to the origin of the human race by a single pair, I al- 
 ways felt that there was a moral objection to it; and I read the Sacred 
 Text with much more satisfaction since I am convinced that it does not 
 require the interpretation usually put upon it. 
 
 There is, again, a physiological objection to the propagation of any 
 animals from a single pair, because this incestuous intercourse tends 
 eventually to the deterioration and extinction of the races that are sub- 
 jected to it. I do not believe that the earth could ever have been fur- 
 nished with animals on this plan, unless a miracle had been wrought at 
 every stage of it. The process of breeding in and in is extremely diffi- 
 cult and often impossible. Sir John Sebright and others have proved 
 this on a large scale with respect to domestic animals \ and the same 
 fact is equally familiar in this country. Azara states that the natives 
 of Paraguay have found from experience that their cattle gradually di- 
 minish in size, and lose their fecundity, unless fresh animals of both 
 sexes are introduced, from time to time from other pastures than their 
 own ;f and Mr. Alexander Walker, after a laborious examination of 
 this question, declares that by this process " nearly perfect beings 
 would eventually degenerate." Here, then, even among our domestic 
 animals, we have a degree of that same difficulty that is proverbial 
 among admitted hybrids. As to man, let us suppose the mulatto offspring 
 
 * Species a primordial organic form. S. G. M. 
 I Quadrupeds of Paraguay, p. 23
 
 18 
 
 of a black man and a white woman (or the reverse) were compelled to 
 marry among themselves, without any access of other individuals of 
 either race, how long do you suppose this mixed breed would last ? 
 Not beyond the third or fourth generation. 
 
 I repeat my matured conviction that the different species of animals 
 were created in their allotted regions of the earth, the kangaroo in 
 New Holland, the sloth in Brazil. They did not appear on the earth 
 in pairs, but in many pairs, some more, some less. A few elephants 
 might serve to stock a continent j but when Prof. Baily informs me 
 that hundreds of millions of Polythalmia, (each one as truly organized 
 as an elephant) exist in a single cubic inch of the sea mud of our own 
 coast, it strikes me as very absurd to suppose that they have been de- 
 rived from a single pair, or had their origin in Mesopotamia. The views 
 I here advance are those of Azara, Swainson, Hamilton Smith, Agassiz 
 and several other eminent zoologists. The recent judicious observa- 
 tions of Prof. Agassiz on this question, in the Christian Examiner, 
 preclude the necessity of any further remarks on my part ; and I shall 
 conclude what I have to say on this head in the words of St. Augustine: 
 " If animals/' says he, "have not been brought to remote islands by 
 angels, or perhaps by the inhabitants of continents addicted to the chase, 
 they must have been spontaneously produced on the earth;" or in other 
 words, in the localities where we now find them. It is difficult for me 
 to imagine that a practical zoologist can entertain a contrary opinion. 
 
 It is one of the weaknesses of mankind to delight in mystery, and to 
 be perpetually looking for miracles. They forget or disregard the fact 
 that the laws of Nature were ordained of God, and that a special inter- 
 position at every step would disjoint the mighty mechanism and mar 
 the harmony of creation. 
 
 I am convinced that the more we study the Mosaic history in connec- 
 tion with Natural Science, the more we shall be instructed by both. Is 
 our faith shaken because Grallileo has shown that the sun does not re- 
 volve round the earth, but the earth round the sun ? Does it detract 
 from our admiration of Creative Wisdom to be told, as Geology teaches, 
 that past time is an eternity ? Should it lessen our admiration of the 
 past, or our hope in the future, to be told that mankind have existed 
 thousands of centuries* upon the earth? Or does our religion suffer de- 
 triment because the great Lepsius has deciphered the legends of Memphis, 
 
 * "Beyond that event (the arrival of Abraham in Palestine) we can never know 
 how many centuries, nor how many chiliads of years may have elapsed since the 
 first man of clay received the image of God and the breath of life." Prichard.
 
 19 
 
 and proved that they date back three thousand five hundred years before 
 Christ ? Yet these things are true ; and if the pride of man feels hu- 
 miliated at his past ignorance, let him be thankful that he has yet lived 
 to see so much light. 
 
 In conclusion, I feel that I owe you an apology for this very long and 
 very diffuse communication, which has been written amid the exacting 
 duties of an arduous profession. I have taken this occasion to publish 
 some facts and to express some opinions which I had designed for a 
 supplement to my Essay on Hybridity, and I shall now leave the further 
 investigation of the subject to other and abler hands. 
 I remain, my dear sir, 
 
 Very faithfully your friend and servant, 
 
 SAMUEL GEORGE MORTON. 
 
 P. S. After I had made considerable progress in the preceding letter 
 I met with a copy of your work on the " Unity of the Human Species," 
 which, with all the interest of its facts and the ingenuity of its argu- 
 ment, would lead me to suppose that Ethnology has stood still while all 
 the other sciences have made such remarkable advances. Ethnology 
 must hereafter be studied in connection with general zoology, geology 
 and chronology ; and even astronomy, in the hands of such men as 
 Humboldt and Lepsius, is a collateral aid of great value.
 
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