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 UNIVERSITY OF ILLINOIS LIBRARY AT URBANA-CHAMPAIGN 
 
 L161 0-1096 
 
A Study of the 
 Cause of "Buttons" 
 
 in the 
 
 J. H. Hale Peach 
 
 By M. J. DORSEY 
 
 UNIVERSITY OF ILLINOIS 
 AGRICULTURAL EXPERIMENT STATION 
 
 Bulletin 458 
 
CONTENTS 
 
 PAGE 
 
 EXTENT OF BUTTON PRODUCTION 4 
 
 OTHER OBSERVATIONS ON CAUSE OF BUTTONS 7 
 
 MATERIALS AND METHODS 8 
 
 OVULE DEVELOPMENT IN RELATION TO BUTTON FORMATION 8 
 
 Ovule Development During the Drops 8 
 
 Ovule Developments After the June Drop 20 
 
 PRESENCE OF DOUBLE SEEDS IN BUTTONS 23 
 
 CONTROL MEASURES TESTED 26 
 
 GENERAL DISCUSSION OF THE PROBLEM 28 
 
 Necessary Steps in Early Fruit Development 28 
 
 Growth Stimulus to Fruit From Fertilization 29 
 
 Departures From Normal Seed Development 33 
 
 Conditions in Embryo Sac of Buttons 35 
 
 Most Probable Cause of Buttons 36 
 
 SUMMARY AND CONCLUSIONS 41 
 
 LITERATURE CITED... . 43 
 
 Acknowledgment 
 
 Urbana, Illinois October, 1939 
 
 Publications in the Bulletin series report the results of investigations made 
 by or sponsored by the Experiment Station 
 
A Study of the Cause of ' Buttons" 
 in the J. H. Hale Peach 
 
 M. J. DORSEY, Chief in Pomology 
 
 O PEACH was ever received with so much enthusiasm from 
 growers and pomologists as the J. H. Hale variety when it was 
 introduced by the Wm. P. Stark Nursery Company, of Stark 
 City, Missouri, in 1912 (Hale 12 *). As it was more generally planted, 
 however, two serious defects became apparent. In the first place, it 
 was reported (Conners 3 *) to bear aborted anthers, and therefore to 
 be pollen-sterile. In the second place growers observed that a variable 
 proportion of the crop in some seasons did not reach full size a but 
 remained upon the tree to ripen somewhat later than the normal fruit. 
 This contrast in size of fruit is shown in Fig. 1. 
 
 These defects were indeed serious in a variety which seemed so 
 promising in the initial tests. Expressions of enthusiasm in the early 
 writings, such as "the million dollar peach" and "Elberta is doomed," 
 soon gave way to adverse criticism when it became apparent that, 
 because of low yield, this variety was not so profitable as it had 
 promised even tho it did command a high price in the market. It is 
 only fair to state, however, in support of the high estimate placed upon 
 its merits after the first tests, that Culpepper and Caldwell 4 * found it 
 to rank above all other commercial freestones grown in the East in 
 retaining its firmness after picking and in holding together in the can- 
 ning process. 
 
 The production of aborted anthers and buttons by this variety 
 would not be so serious were it not for the fact that it also falls short 
 of some of the other varieties in hardiness of fruit bud and in vigor of 
 growth. Because of these shortcomings, J. H. Hale has not been set 
 so extensively in commercial orchards in the last decade as previously. 
 Nevertheless the unusually attractive appearance and carrying quality 
 of the fruit still make it a favorite in the "fancy" trade, especially 
 when distance shipments are involved. 
 
 "The small fruits borne by this variety have become known by different 
 names, such as "buttons," "runts," "nubbins," or simply the "little fellows." 
 The term "button" first used in 1922 in New Jersey (Blake et a/ 1 *) will be used 
 in this connection because its use with this meaning has become well established 
 among peach growers. 
 
 These and similar numbers thruout the text refer to literature citations, 
 page 43. 
 
 3 
 
4 BULLETIN No. 458 [October, 
 
 Recognizing that there is considerable interest in J. H. Hale among 
 peach breeders, and that it is still an important variety in some places, 
 it seemed advisable to determine, if possible, the cause of the retarded 
 growth which terminates in buttons. This information would, of 
 course, serve also as a basis for understanding this problem in what- 
 ever variety of the peach it may occur. 
 
 EXTENT OF BUTTON PRODUCTION 
 
 Button production is quite variable from year to year. While in 
 extreme instances as many as 90 percent of the peaches which remain 
 upon the tree after the June drop may develop into buttons, generally 
 the proportion is not so large. In some orchards the button problem 
 seems to be much less serious over a period of years than in others. 
 Trees in good vigor may not produce buttons one season but in the 
 next season may bear buttons in abundance. Old trees seem to produce 
 more buttons the year following a heavy crop, but this relationship 
 is not constant. Sometimes only a few trees in an orchard will bear 
 buttons. In one instance in 1931 a single limb on a fourteen-year-old 
 J. H. Hale tree bore buttons in clusters, while the remainder of the 
 tree was practically free from them. The seriousness of button pro- 
 duction in this variety will be seen from the following records. 
 
 In a J. H. Hale block in the Bates orchard near Centralia, which 
 was under observation in 1929, button production was quite general. 
 In a careful count of the crop on ten typical trees the first of August, 
 the following condition was found: The number of buttons ranged 
 from 79 to 356 per tree and the number of normal fruits from 76 to 
 404 per tree. The total number of buttons on these ten trees was 
 1,784; the number of normal fruits, 2,012. The tree which bore the 
 largest number of buttons, 356, produced only 115 normal fruits. In 
 this same orchard the years 1927, 1928, 1929, 1933, and 1935 were 
 "button years," while in 1926 and 1931 practically no buttons were 
 produced. 
 
 An unusual situation developed in another orchard in southern 
 Illinois in the spring of 1936. Fruit-bud survival after the winter 
 temperatures was about 8 percent enough for a crop if all were to 
 set and mature. Sometimes good crops are produced under just such 
 conditions. But in this orchard freezing temperatures occurred during 
 bloom and only a few of the fruits developed normally altho there 
 was an abundance of buttons. This instance would seem to bear out 
 the suggestion that buttons result from low-temperature injury. 
 
1939] 
 
 CAUSE OF "BUTTONS" IN J. H. HALE PEACH 
 
 FIG. 1. A NORMAL J. H. HALE PEACH AND Two "BUTTONS" 
 
 JUST BEFORE HARVEST 
 
 (Natural size) 
 
6 BULLETIN No. 458 [October, 
 
 Still another opportunity arose in the spring of 1938 to observe 
 button production in an orchard near Flora, Illinois. J. H. Hale had 
 been planted alternately in 4-row blocks with Elberta. The weather 
 was unfavorable for bee flight during bloom, altho there was an 
 abundance of bloom for a crop. At first it seemed that the set was 
 going to be heavy, owing to a very light first drop, but as the season 
 advanced the second drop was excessive, leaving only 300 to 500 
 fruits per tree. The June drop proved to be light on both J. H. Hale 
 and on the adjacent trees of Elberta. On June 24, after all three 
 of the drops were over, the number of normal peaches on fifteen J. 
 H. Hale trees was as follows: 16, 9, 26, 20, 6, 18, 17, 18, 33, 14, 6, 
 33, 7, 20 and 22. The number of buttons on these same trees was 
 estimated to vary between 150 and 500. These trees were seven years 
 old and capable of bearing a full crop of four or five bushels each. 
 This was the most extreme case of button production observed during 
 this study. 
 
 The production of buttons by J. H. Hale is also serious in other 
 sections of the country. Conners 3 * says: "In some orchards [in New 
 Jersey] this variety will produce a full crop of large, fine peaches, 
 while in an orchard only a short distance away the crop will be prac- 
 tically all buttons." From the Grand Junction District of Colorado, 
 Mr. Silman Smith writes: "The trees bore very nicely as four-year- 
 olds; but as five-year-olds, last year, most of the crop consisted of 
 buttons."* Other records of a similar nature might be given, but these 
 will suffice to illustrate the situation with the variety elsewhere. 
 
 In other varieties button production is not so serious, altho it has 
 been noted in Globe and Crosby (Stewart and Eustace 22 *), St. John, 
 Fox, Elberta, Foster (Conners 3 *), Bilmeyer, Bridgon, Early Crawford 
 and Richmond (Palmer 19 *). The writer observed an instance in 1896 
 in northern Muskingum county, Ohio (similar to that of Heister 
 below), in which the entire crop of Early Crawford and a local yellow 
 freestone known as Crabtree were buttons. Buttons have also been 
 found recently in some of the newer varieties, such as Halberta and 
 Fertile Hale. 
 
 It is apparent, then, that this condition may occur in other varieties 
 although the experience of growers shows that the problem is centered 
 for the most part in the variety J. H. Hale. The economic impor- 
 tance of the button situation, therefore, lies in the fact that a full crop 
 in prospect may be reduced to an unprofitable partial crop as in the 
 instance reported by Heister. 15 * 
 
 Personal letter, May 19, 1930. 
 
1939} CAUSE OF "BUTTONS" IN J. H. HALE PEACH 7 
 
 OTHER OBSERVATIONS ON CAUSE OF BUTTONS 
 
 A survey of the literature shows that buttons have been ascribed 
 to a number of causes. Heister 15 * made the following record of a 
 personal experience: 
 
 "In 1896 about 3,000 of my trees bore a crop of little peaches .... I cut 
 a great many of them at different times but not a single one had a kernel in the 
 pit .... I, at the time, decided that owing to some unfavorable climatic 
 condition, the blossoms were not properly fertilized and as there was no seed 
 to ripen, there was no growth to the peach." 
 
 The varieties in the Heister orchard were not given, but it is stated 
 that these same trees bore an abundant crop of perfect peaches the 
 next year. Stewart and Eustace 22 * and Palmer 19 * also think buttons are 
 a result of "imperfect fertilization." 
 
 Conners 3 * says that these buttons behave as if fertilized, as un- 
 fertilized blossoms drop as soon as the petals fall. He writes: 
 
 "If pollination has been accomplished, complete fertilization has not taken 
 place. This may be due to the pollen tube being slow in growth so that the 
 tube nucleus enters the ovum at a period too late for fusion. The development 
 of buttons would then be an expression of vegetative vigor." 
 
 In a personal letter to the writer (October 10, 1936) Blake says 
 that buttons are "always present following a season when there is cold 
 injury to the flowers and twigs." He states further that buttons are 
 "brought about by the effect of low temperatures upon the stem of the 
 fruit or near its attachment which disturbs the normal movement of 
 nutrients." Something of the same idea is set forth by Harrold, 13 * 
 in a discussion of drops, when he suggests that "in the course of 
 abortion, development stops first in the region of the chalaza and ex- 
 tends from there to other parts of the seed and fruit. 
 
 The writer in 1928 (Dorsey 9 *) stated that "the causes leading up 
 to the formation of buttons appear to be centered about the early 
 stages of development of the young fruit." 
 
 It will be seen from these quotations that both weather and polli- 
 nation have been suspected of having a bearing upon the production 
 of buttons. Either of these would place the cause of buttons "at the 
 early stages of development." The exact way in which cold injury 
 to the "flowers and twigs" may cause buttons is not clear, but evidence 
 of this relationship needs critical study. It is possible, also, that the dis- 
 order in the region of the chalaza, which Harrold suggests may "dis- 
 organize the vascular system," is in reality a consequence of a deeper- 
 seated factor. Further consideration will be given to these ideas in the 
 general discussion, pages 28 to 40. 
 
8 BULLETIN No. 458 [October, 
 
 MATERIALS AND METHODS 
 
 The first material for this study was collected in 1926 from J. H. 
 11 ale trees which were known to be true to name. Since then fruit 
 production in this variety has been studied in a number of orchards in 
 this state and also in the Grand Junction area in Colorado and in the 
 Wenatchee Valley, Washington. The collections of flowers or imma- 
 ture fruits, however, were made primarily from trees in the orchard 
 of D. I. Rates and Son, near Centralia, Illinois. Rawlins fixing fluid 
 was used exclusively in this work and proved very satisfactory. 
 
 Fortunately the collections in the Bates orchard included the 
 seasons of 1929 and 1931 two years with the greatest contrast in 
 button production in this orchard and in the state in general. A 
 parallel series of pistils was collected in 1933 for comparison from 
 Elberta trees growing on the University farm near Olney. 
 
 The usual cytological technic was followed in embedding and sec- 
 tioning. Heidenhains iron alum hematoxylin was used, for the most 
 part, in staining, altho good results were obtained with other stains. 
 
 OVULE DEVELOPMENT IN RELATION TO 
 BUTTON FORMATION 
 
 This section is devoted to a critical examination of ovules at 
 various growth stages between full bloom and the collapse of the seed 
 about the beginning of the third growth period. This approach to the 
 problem was decided upon because it is impossible to tell which fruits 
 will develop into buttons until after the June drop. Even tho this is 
 true, however, it seemed necessary to study the early stages of de- 
 velopment in order to determine whether or not there might be con- 
 ditions present even then which could be related to button production. 
 Admittedly there is some uncertainty in this procedure, but of course 
 it is impossible to study the internal condition of a pistil and at 
 the same time leave it intact on the tree to complete its normal growth. 
 
 The materials on this phase of the problem will be presented in two 
 main parts: (1) the development of the ovule in buttons during the 
 period of the three drops; and (2) the condition found in the seed 
 after the drops are over, when buttons can first be selected with 
 certainty. 
 
 Ovule Development During the Drops 
 
 Development at Bloom. Sections of the early pistil stages of 
 J. H. Hale show that the growing point of the ovule in the latitude 
 of southern Illinois is present as early as the middle of March. The 
 
1939] CAUSE OF "BUTTONS" IN J. H. HALE PEACH 9 
 
 megaspore mother cell, however, is not found until 10 to 12 days 
 before bloom. The growth of the ovule as a whole is relatively rapid 
 after the megaspore appears, and up to full bloom the embryo sac, 
 nucellus, and seed coats undergo the characteristic development of 
 the rosaceous plants, as outlined by Pechoutre. 20 * 
 
 The divisions of the embryo-sac nuclei seem to take place somewhat 
 later in J. H. Hale than in Carman, as reported by Harrold, 13 * but this 
 point is difficult to check accurately on account of the variation found 
 in the rate or time of development in different pistils. Thus in one 
 series of apparently normal flowers of J. H. Hale collected in 1929 
 at full bloom the following condition was found in the most advanced 
 ovule of each of the 24 pistils sectioned for examination: in 1 ovule 
 a megaspore had not developed, in 4 a megaspore was present, and 
 in 4 a megaspore was present but degenerating. In the ovules of this 
 lot in which the condition in the embryo sac seemed normal, there was 
 a single nucleus in one sac, two nuclei in 3 sacs, three nuclei in 3 
 sacs, four in 5 sacs, while only 3 sacs had the full nuclear content 
 of eight (Table 1, line 1). 
 
 The condition just described was typical of the other series in J. 
 H. Hale, and of Elberta as well, which were examined at full bloom. 
 In some instances apparently normal embryo sacs did not have eight 
 nuclei as late as one week after bloom. It is quite probable that ferti- 
 lization would not take place in these sacs if it had already occurred in 
 the more advanced pistils. 
 
 Because of so much variation in the nuclear content of the embryo 
 sac at the early stages it does not seem possible to definitely relate 
 a given condition at this time to button formation. It would seem safe 
 to state, however, in view of the three drops which are next described, 
 that the normal fruits would come from those pistils in which the 
 growth and functioning of all of the nuclei in the embryo sac had 
 proceeded normally. 
 
 Sixteen Days After Bloom. At this time in 1929 the young fruits 
 of J. H. Hale in the Bates orchard averaged about % inch in di- 
 ameter and the first drop was nearly over. Slight size differences 
 between the pistils were apparent, but the weaker or aborted ones had 
 already been eliminated by the first drop. Not a single case in which 
 either the zygote or endosperm nuclei had divided was found in 18 
 pistils sectioned (Fig. 2, a-d). In view of the variation noted in the 
 embryo-sac nuclei at bloom, some variation in the nuclear content might 
 still be expected even tho some pistils had been eliminated. Thus, in 
 this sample of 25 pistils there were 4 sacs with no nuclei, 11 with one, 
 
10 
 
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1939] 
 
 CAUSE OF "BUTTONS" IN J. H. HALE PEACH 
 
 11 
 
 4 with two, 3 with three, 2 with four, while only one sac as late as this 
 had the full nuclear content of eight (Table 1, line 2). This one was 
 probably a late flower. Division had not as yet taken place in the fusion 
 nucleus in any of the pistils of this collection. The presence of a single 
 nucleus in 11 sacs is an interesting feature of this collection. This cell 
 was always in the position in the sac of the female gamete, so it is 
 improbable in these cases that a fusion nucleus was formed. In the 
 absence of fusion, the two nuclei which are destined to form the fusion 
 nucleus by their union are apparently absorbed in much the same 
 manner as the synergids and antipodals. 
 
 It will be seen from Table 2 that at the 16-day period the first drop 
 was normally under way. The abscission of those pistils with a single 
 nucleus in the embryo sac in the second drop may be assumed if this 
 
 TABLE 2. COMPARISON OF GROWTH STATUS OF THE DIFFERENT PISTIL OR FRUIT 
 TYPES FOUND IN THE PEACH 
 
 Fruit type or 
 growth stage 
 
 Size reached 
 before falling 
 
 Limit of 
 
 persistence 
 
 Stone 
 length 
 
 Seed 
 length 
 
 Time of browning 
 of seed coats 
 
 First drop of 
 
 Full bloom 
 
 About 3 weeks 
 
 
 
 
 aborted pistils 
 
 H-H" 
 
 30 to 50 days 
 
 
 !6-Me" 
 
 20 to 30 days 
 
 nonpollinated 
 pistils as in 
 Elberta 
 
 
 after bloom 
 
 
 
 after bloom 
 
 June drop in 
 Elberta and 
 J. H. Hale 
 
 H-lH* 
 
 40 to 60 days 
 after bloom 
 
 Undergoes 
 partial 
 develop- 
 ment 
 
 H-H' 
 
 Fruits usually 
 fall before 
 seed coats 
 turn brown 
 
 J. H. Hale 
 buttons 
 
 1H-2/4" 
 
 Until after har- 
 vest, 110 to 
 
 1-1 H* 
 
 &-H* 
 
 50 to 80 days 
 after bloom 
 
 
 
 120 days 
 
 
 
 
 Buttons with 
 killed seeds 
 
 1H-2J4" 
 
 Until after har- 
 vest, 110 to 
 120 days 
 
 1-1 H* 
 
 J4-M* 
 
 Soon after 
 being 
 frozen 
 
 Elberta with 
 killed seeds 
 
 Full size 
 
 Harvest time 
 
 Nearly 
 full 
 size 
 
 H" or so 
 
 Soon after 
 being 
 frozen 
 
 Normal J. H. 
 Hale fruit 
 
 Full size 
 2H-3H" 
 
 Until harvest, 
 110 to 120 
 days after 
 bloom 
 
 1 M-m" 
 
 K-ft* 
 
 Second 
 growth 
 period 
 
 type is not found in later collections. If these pistils are disposed of 
 in this way, then a single nucleus in the embryo sac as early as this is 
 of no significance in connection with the buttons. Since 1929 was such 
 a pronounced "button year," it will be interesting to compare the 
 nuclear content of the embryo sac of these pistils with those collected 
 in 1931 at the same relative growth stage, when there were practically 
 
, :< 
 
 J 
 
 Mr -M 
 
FIG. 2. CONDITIONS IN EMBRYO SAC AT EARLY STAGES 
 
 a An embryo sac 15 days after bloom with only two nuclei presum- 
 ably the zygote and the endosperm nucleus. 
 
 b A higher magnification of a zygote 15 days after full bloom, show- 
 ing distended wall and distal position of nucleus in zygote in 
 relation to the micropyle. 
 
 d Undivided endosperm nuclei 15 days after bloom. 
 
 / Retarded development in embryo-sac structures three weeks after 
 bloom. 
 
 h Appearance of undivided endosperm nucleus three weeks after 
 
 bloom. 
 i An embryo 23 days after bloom. Note endosperm nuclei. 
 
 / An endosperm mass in a sac in which there was a zygote remnant, 
 23 days after bloom. 
 
 k An embryo sac in which the nuclei had been absorbed or com- 
 pletely disintegrated. 
 
 / An undivided zygote nucleus 23 days after bloom. Only a deeply 
 stained remnant was in the position of the endosperm nucleus. 
 

FIG. 3. RETARDED CONDITION IN EMBRYO SAC OF J. H. HALE BUTTONS 
 47 DAYS AFTER FULL BLOOM 
 
 a-d Advanced stages of disintegration and absorption in contents of 
 
 embryo sac. 
 e-h Some of the variables encountered in the condition of the zygote 
 
 at this stage. Only g shows endosperm remnants. 
 i-l Some endosperm development has taken place but apparently no 
 
 division of the zygote. 
 
16 BULLETIN No. 458 [October, 
 
 no buttons. The season of 1931 was unusually favorable for growth 
 in the early spring, and because of a crop failure the year before, the 
 trees had "had a rest." Under these conditions the crop of 1931 was 
 not only the heaviest on record in this orchard but in the state as well, 
 and there were very few buttons produced by J. H. Hale during this 
 season. 
 
 One collection of pistils was made on April 18, 1931, fifteen days 
 after bloom. From this lot 75 ovules were sectioned for study and 
 compared with those taken in 1929 (Table 1, line 3). Of this number, 
 the embryo sac was aborted in nine. In 3 embryo sacs of the lot 
 there was one nucleus, in 62 there were two, and in 1 there were 
 three. The two-celled condition of the sac was typical of this lot and 
 contrasts with the one-celled condition found in the smaller 1929 
 sample collected at about the same time after bloom. The general ap- 
 pearance of the sac justified the conclusion that one of these nuclei 
 was the egg a and the other the fusion nucleus. 
 
 The development in the embryo sac in these two lots is interesting 
 in view of the extremes in button production during the seasons of 
 1929 and 1931. It may be assumed from the 1931 material that the 
 endosperm nucleus did not normally divide in the more vigorous pistils 
 in this variety earlier than two weeks after full bloom. On the other 
 hand, the other nuclei of the embryo sac did not persist much longer 
 than two weeks. It was, of course, impossible to determine from the 
 appearance of the egg and the fusion nucleus whether or not fertili- 
 zation (i.e., double fertilization) had taken place, and it is very difficult 
 to check the actual time of gametic fusion in any considerable number 
 of pistils. It is probable, however, in view of the results with other 
 fruits, that under the most extreme instances of delay, gametic fusion 
 takes place in the peach within a two-weeks period after full bloom. 
 The absorption of the antipodals and synergids would indicate that in 
 1931 development in the embryo sac was normal in most instances. 
 Four of the sacs of the 1929 collection, it will be noted, run parallel 
 with the binucleate condition in 1931. Up to this time, then, it does 
 not seem possible to detect any irregularities which can be related 
 to buttons. 
 
 Twenty-Three Days After Bloom. The 188 pistils collected 23 
 days after bloom in the Bates orchard in 1929 averaged about % inch 
 in diameter. The "shuck," or calyx, had been thrown off in most cases. 
 
 'For convenience, after the normal time of fertilization has been reached 
 and passed, the cell in the embryo sac in the position of the egg will be called 
 the zygote, even tho it is necessary to assume that fertilization has taken place. 
 
1939] CAUSE OF "BUTTONS" IN J. H. HALE PEACH 17 
 
 Altho the first drop was over when this collection was made, the non- 
 pollinated fruits were still on the tree ; and while there was some 
 difference in size, it was still difficult to separate the fruits undergoing 
 normal development from those which would be cut off at the second 
 drop. 
 
 A critical study of these 188 pistils revealed the following con- 
 ditions (Table 1, line 4). A single cell was present in the position of 
 the egg or zygote in 195 ovules (including 7 double ovules). In some 
 instances this nucleus was broken down and disorganized, and as a 
 result it stained deeply (Fig. 2, e, g, i, /). Two nuclei were present 
 in the micropylar end of a sac in only three instances. An embryo, 
 five to eight cells in diameter, had developed in only three sacs ; 
 and in each of these, endosperm nuclei were present in varying num- 
 bers (Fig. 2, i). There was no endosperm to be found in the other 
 sacs 185 in number but in nearly all of them the fusion nucleus was 
 still present (Fig. 2, g, i, /). 
 
 The ovule had, of course, undergone many structural changes since 
 the former collection at about the two-week period. The embryo sac 
 had extended further into the "canal," or opening, that had formed in 
 the nucellus. The peculiar crinkled appearance of the sac in so many 
 cases (Figs. 2 and 3) indicated something of its lack of normal growth 
 or elongation in the absence of endosperm formation. In these same 
 ovules the canal had increased in length and depth independently of 
 embryo-sac extension. It would seem that a state of development had 
 been reached at the time of this collection when it was increasingly 
 necessary for the pistil structures to complete their normal growth if 
 the fruit was to persist and grow. 
 
 In order to evaluate the situation just described, in relation to 
 button production, comparison will be made with normal development 
 in Elberta in which buttons seldom, if ever, occur (Table 1, line 5). 
 In 15 normal pistils of Elberta collected 20 days after bloom in 1933, 
 from the Olney farm, the zygote had divided in only two. Endosperm 
 nuclei were present in varying numbers in all of the sacs except one, 
 in which the fusion nucleus had not yet divided. This pistil was prob- 
 ably the most retarded of the lot because in it the embryo sac had 
 extended into the canal only about one-fourth of the length of the 
 nucellus. In the others the embryo sac was about one-half extended 
 in 4, two-thirds extended in 5, and fully extended in the 5 remaining 
 pistils of this lot. 
 
 At the three-week period, while it was still impossible to determine 
 which pistils would form buttons, it was of considerable interest to 
 note the retarded development in such a large proportion of the 
 
18 BULLETIN No. 458 {October, 
 
 ovules of J. H. Hale in a "button year." The absence of endosperm 
 nuclei in so many pistils is especially significant in view of the fact that 
 the time had arrived when there were endosperm nuclei in what ap- 
 peared to be normal pistils of both J. H. Hale and Elberta. The 
 presence of an embryo and endosperm nuclei in three of the ovules in 
 the 23-day collection of 1929 may be taken as normal development 
 in J. H. Hale at this period for the most advanced pistils. It should 
 be noted that Harrold 13 * found the zygote nucleus divided in the 
 variety Carman, growing under Georgia conditions, as early as 12 days 
 after fertilization. 
 
 Emphasis should be placed on the fact that division in the endo- 
 sperm nucleus precedes division in the zygote by a week or so. This 
 raises a very important point in connection with button formation: viz., 
 will the zygote nucleus divide if the endosperm nucleus does not? This 
 point will be stressed in the discussion when the condition in the 
 embryo sac in the later collections has been described. 
 
 Before passing on to a discussion of the next collection, special 
 mention should be made (a) of the persistence of two nuclei pre- 
 sumably the egg and the fusion nucleus in such a large proportion of 
 the J. H. Hale pistils, (b) the retarded development in the endosperm 
 as compared with Elberta; and (c) the absence of pistils with a single 
 nucleus in the sac such as was found in the 16-day collection. 
 
 Thirty-Five Days After Bloom. The next collection was made 
 on May 8, 1929, or a little more than a month after bloom. At this 
 time there was still more difference in the size of the young fruits 
 than at the' 23-day period. The second drop was under way, but it 
 was not extensive ; so as late as this it was still impossible to select 
 buttons with certainty. There had been considerable enlargement in the 
 ovule since the previous collection. The central cells of the nucellus 
 adjacent to the funiculus were brownish in color and somewhat broken 
 down in many, but not in all, of the ovules examined, indicating 
 further disturbance in that region in some instances. At this stage the 
 embryo sac showed the peculiar crinkled appearance already noted, 
 but in an increasing degree. 
 
 Observation of the sections showed many variables in the contents 
 of the embryo sac (Table 1, line 6). In one sac both the zygote and 
 the fusion nucleus appeared normal even tho they had not divided. In 
 6 others both were greatly distended and showed advanced stages of 
 degeneration. It was interesting to find that as the zygote became 
 distended, the nucleus was basal (i.e., away from the micropyle) to a 
 single large vacuole. In 7 sacs a zygote was present in various stages 
 
J9J9] CAUSE OF "BUTTONS" IN J. H. HALE PEACH 19 
 
 of distension and disintegration but in none of these could the fusion 
 nucleus be found. It is probable that in these sacs this nucleus had 
 been absorbed after its disintegration, since it is not likely that a 
 pistil would persist for so long if growth in it was not sufficiently 
 vigorous for embryo-sac development to be carried that far. In one 
 instance, in a double seed, the sac was empty and in two the zygote 
 was absent, altho in one sac there were a few endosperm nuclei. In 
 6 pistils a normal-appearing embryo a few cells across had developed, 
 and the endosperm nuclei were in active division. These were appar- 
 ently the normal pistils of this lot of 22 selected at random. 
 
 The expansion of the membrane of the zygote in the retarded 
 pistils, where it still persisted as such, and the diffused staining of the 
 cytoplasm indicated that the approximate limit of the functional period 
 had been reached. In fact, the sac itself was often folded and crinkled, 
 a very interesting internal condition in young fruits that have persisted 
 up to the time limits of the second drop. 
 
 Forty Days After Bloom. The next collection in 1929 was made 
 on May 14, about 40 days after full bloom. The difference between, 
 the size of the normal fruits and those falling behind in growth was 
 about as follows: The largest of the normal peaches were % inch 
 thru the suture diameter, while the retarded fruits averaged about 
 %e mc h in diameter about the upper limit of the size reached by 
 non fertilized pistils. The size of the kernel in these two groups was 
 roughly proportional to the outside dimensions, the length in the larger 
 fruits averaging about % inch and in the smaller ones nearly % inch. 
 With this difference in size between the two groups still persisting, and 
 with the June drop under way, it would seem safe to assume that a 
 part of the fruits in this collection would develop no further than 
 buttons. 
 
 From this collection sections were made of 93 ovules. Of this 
 number, a zygote was present in 65. No trace of either a zygote 
 or an embryo could be found in 21 ovules, yet these came from 
 the normal-appearing smaller peaches. Endosperm nuclei were present 
 in 24 sacs, but in 62 none could be found. In most of the latter the 
 fusion nucleus still persisted but was badly disorganized or distended.. 
 Both an embryo and endosperm nuclei were found in only 7 embryo 
 sacs in this collection (Table 1, line 7). The canal had extended the 
 full length of the nucellus in all of the ovules, but the embryo-sac ex- 
 tension was quite variable, being fully formed in only a few instances. 
 Even with this internal condition the outer seed coats were whitish in. 
 color and the ovule was still plump. 
 
20 BULLETIN No. 458 [October, 
 
 It will now be of interest to compare again' the development in 
 normal ovules of Elberta and J. H. Hale. These comparative studies 
 show that embryo and endosperm growth in Elberta (from the 1933 
 collections at the Olney farm) and normal-appearing, larger fruit of 
 J. H. Hale progress thru the season at about the same rate. This 
 would be expected, since these two varieties ripen so nearly at the 
 same time. The condition in the larger pistils of either of these two 
 varieties might, therefore, be taken as the normal status for the par- 
 ticular stage of development in question. 
 
 In sections of Elberta pistils at the 40-day period an embryo six to 
 eight cells across was always present (Table 1, line 8). It has been 
 pointed out (Dorsey and McMunn 8 *) that as late as two months after 
 bloom the embryo in Elberta is still small, generally no more than % 6 
 to % inch in diameter. In contrast to the retarded growth in the em- 
 bryo, division proceeds rapidly in the endosperm nuclei, so that at the 
 40-day period the embryo sac is fully extended into the canal and is 
 lined by endosperm nuclei thruout its length. At the 40-day period, 
 development in the embryo and endosperm in buttons on the J. H. 
 Hale was far behind that in normal peaches of either J. H. Hale or 
 Elberta. 
 
 Ovule Developments After the June Drop 
 
 Forty-Seven Days After Bloom. The next collection in the 1929 
 series was made on May 20, which was 47 days after full bloom. 
 The June drop was over; so in this instance for the first time buttons 
 could be definitely selected because of the contrast in size between 
 them and the normal peaches. 
 
 After the drops were over, there still remained on the tree two 
 groups of peaches differing greatly in size. The buttons which persist 
 until harvest must, therefore, be derived from this retarded group. 
 After the June drop, however, there is still a slight loss of buttons 
 thruout the summer, especially if buttons make up a large proportion 
 of the crop. This loss always comes from the smaller sizes, which 
 wither and assume a yellowish cast before falling (Fig. 4). This would 
 indicate some competition, or at least some difference, between the 
 buttons themselves ; it was shown by the writer (Dorsey 9 *) that normal 
 peaches are physiologically dominant over buttons. 
 
 In view of the persistence of the contents of the embryo sac in 
 the previous collections even tho the zygote showed advanced stages 
 of disintegration, it will now be of interest to note the condition in 
 buttons at the 47-day period (Table 1, line 9). 
 
 In the ovules sectioned for examination there was not a single 
 
1939] CAUSE OF "BUTTONS" IN J. H. HALE PEACH 21 
 
 FIG. 4. SIZE RANGE IN FRUIT OF J. H. HALE AT END OF JUNE DROP 
 Note withered condition of the smaller buttons. (Natural size.) 
 
22 BULLETIN No. 458 [October, 
 
 instance in which there was a normal development for this growth 
 stage in either the embryo or the endosperm (Fig. 2). The variation 
 found in these structures was interesting. Of the 30 ovules sectioned 
 for study, the zygote nucleus was still recognizable in 24 but had ap- 
 parently been absorbed, if it had been formed, in 6. The endosperm 
 nucleus had divided and a few nuclei were present in 4 ovules ; but it 
 could be recognized, altho in various stages of disintegration, in 13 
 of the others. In the 13 remaining ovules of this lot the zygote was 
 present but the endosperm nucleus had been absorbed, leaving only a 
 single nucleus in the embryo sac. An interesting feature of this lot 
 was the absence of a simultaneous development of the embryo and the 
 endosperm, and the relatively large number of ovules (19 out of 30) in 
 which either one or the other could not be found. 
 
 Thus the condition in the buttons closely parallels that found in 
 the earlier collections, when it could not be stated definitely which 
 fruits would develop into this type. The remnants of the zygote, 
 embryo, fusion nucleus, and endosperm found in the buttons fit into the 
 series terminating with the previous observations. All these structures, 
 when present in buttons, were undergoing disintegration, and the most 
 advanced development found in any of the buttons was far behind 
 that of the normal peaches. 
 
 Final Stages. With the picture of suppressed or retarded growth 
 in the embryo and endosperm in mind, as outlined above, there now 
 remains to be noted the final disposition of the seed and its contents in 
 the buttons. The examination has thus far included pistils collected at 
 intervals extending from bloom, thru the period of the three drops, 
 on to the time when buttons could be singled out with certainty from 
 the normal peaches. The 1929 collections did not extend beyond the 
 47-day period after bloom, for it was thought that the contents of the 
 embryo sac would probably not persist beyond that time. When it was 
 found, however, that this was not the case, it seemed advisable to 
 make still later collections in order to follow the ovule parts thru the 
 final stage of suppression, disintegration, and even absorption. 
 
 The next collection was therefore made 80 days after full bloom 
 (Table 1, line 10). These buttons were divided into two groups, 
 large and small, and these two groups were further divided according 
 to number of ovules which had developed and the coloring of the seed 
 coats. 
 
 While the number of ovules in the different categories is not large, 
 nevertheless this series, collected in 1937, shows about the same de- 
 velopment in the embryo and endosperm as the buttons showed in the 
 
1939~\ CAUSE OF "BUTTONS" IN J. H. HALE PEACH 23 
 
 earlier collections. The persistence of a single cell in the sac in the 
 position of the zygote and the absence of an endosperm nucleus is an 
 interesting feature of these ovules, because it shows that after a certain 
 stage the endosperm nucleus tends to be absorbed much the same as the 
 endosperm. At this late stage too a considerable number of ovules were 
 devoid of a zygote. As with the other collections made at an earlier 
 stage, the endosperm had developed to varying degrees but embryos 
 were present in only a few cases. This series then shows an internal 
 condition which may be looked upon as simply a persistence or a 
 continuation of the earlier condition in buttons found in other years. 
 
 A word should be added as to the final stages in the suppression 
 of the seeds in buttons. Soon after the seed coats turn brown, near the 
 end of the second growth period or during the early part of the third, 
 the liquid content of the seed is withdrawn and in a short time the 
 nucellus collapses. All that remains of the kernel at the end of the 
 growing season, then, is the brown, empty, compressed seed coats. 
 Sometimes the seed coats are broken loose from the placenta, in which 
 case there is often a slight exudation of gum in the stone cavity. 
 
 This, then, is the course of events in the ovule and seed of buttons. 
 The suppression of the ovule and the endosperm is typical of the final 
 stages. The persistence of the remnants of these structures for so long 
 is not surprising in view of the retarded activity in the growth of the 
 button as a whole. In spite of the internal condition, however, fruits 
 of this type persist and even undergo a remarkable enlargement in 
 the final swell. 
 
 PRESENCE OF DOUBLE SEEDS IN BUTTONS 
 
 Still another characteristic of buttons deserves consideration the 
 partial development of both ovules. While in the peach two ovules 
 normally start to develop, one is suppressed in most instances. This 
 condition is also typical of the plum (Dorsey 7 *), in which the time of 
 suppression was found to vary considerably in different species. This 
 point was given some attention in the peach by Harrold, 13 * who found 
 that in the variety Carman the suppression of one ovule took place 
 normally before bloom or at least before fertilization. Under normal 
 conditions two seeds sometimes develop in some of the other com- 
 mercial varieties. Thus in two varietal combinations in the green- 
 house crosses the following condition was found in 1933: among 
 224 normal peaches of J. H. Hale X Gage there were three that had 
 "double seeds," and in 169 fruits of Gage X Elberta' picked at ma- 
 turity there were three that were "doubles." The seed condition in 
 
24 
 
 BULLETIN No. 458 
 
 [October, 
 
 buttons, however, is quite different from that in normal peaches, as 
 will be seen from Table 3. 
 
 While the data in Table 3 show that there is some variation from 
 year to year in the proportion of double seeds in buttons of J. H. Hale, 
 the number is much larger than in normal peaches. The development 
 of both ovules to the extent found in buttons, however, is evidently not 
 a deciding factor in button production, for buttons are also found with 
 a single ovule partially developed. Double ovules may, therefore, 
 be taken as an index of the extent to which there is a parallel develop- 
 ment in the two ovules in this variety before fertilization becomes a 
 deciding factor in the early stages of growth. The size of the seed- 
 coat remnant of the suppressed ovule in normal peaches is comparable 
 
 TABLE 3. CLASSIFICATION OF BUTTONS, AFTER THE JUNE DROP, WITH REFER- 
 ENCE TO SINGLE OR DOUBLE SEED CONDITION, J. H. HALE 
 
 Year collected 
 
 Location 
 
 Number with 
 one seed 
 
 Number with 
 two seeds 
 
 Total 
 
 1927 
 
 
 27 
 
 26 
 
 53 
 
 1927 . 
 
 
 83 
 
 38 
 
 121 
 
 1928 
 
 Centralia 
 
 149 
 
 144 
 
 293 
 
 1929 . 
 
 
 233 
 
 36 
 
 269 
 
 1937 
 
 
 487 
 
 110 
 
 597 
 
 1938 
 
 
 174 
 
 71 
 
 245 
 
 Total 
 
 
 1 153 
 
 425 
 
 1 578 
 
 
 
 
 
 
 to that in buttons. This indicates that in the absence of fertilization 
 suppression in the second ovule takes place at about the same stage in 
 both buttons and normal peaches. In buttons, therefore, something 
 has happened to the second ovule which does not ordinarily happen in 
 the normal peach. Since the two ovules in buttons are so nearly the 
 same size even tho partly suppressed, it would seem logical to assume 
 that similar development has taken place in both of them. 
 
 During midsummer considerable variation is always apparent in 
 the size of buttons. It therefore seemed advisable to determine whether 
 or not this difference was related to the double-seeded condition. The 
 data collected on this point during three seasons have been brought 
 together in Table 4. 
 
 The collections recorded in Table 4 were made, it will be noted, 
 at about the same time after bloom. Each lot was divided into three 
 size-groups and one wilted lot to include the buttons that were being 
 eliminated by late summer abscission. These categories were further 
 divided according to the seed number and the seed-coat color, but 
 
1939] 
 
 CAUSE OF "BUTTONS" IN J. H. HALE PEACH 
 
 25 
 
 no significant relationship could be observed between the partial de- 
 velopment of both ovules and either size or the time of browning of 
 the seed coats. The collections were made early enough in 1929 and 
 1937 to include a considerable proportion of wilted buttons, which 
 would have been eliminated by abscission within a few days. 
 
 There is one significant feature of the 1938 data which was not 
 encountered in either of the other two seasons in nearly one-fourth 
 of the buttons the developing ovule had aborted at an early stage. Six 
 
 TABLE 4. SIZE, SEED CONTENT, AND COLOR OF THE SEED COATS OF BUTTONS 
 NEAR END OF SECOND GROWTH PERIOD 
 
 Color of 
 seed coats 
 
 Number of buttons in the different 
 size-groups on date of collection 
 
 Large Medium 
 
 Small 
 
 Wilted 
 
 Total 
 
 1929: 84 days after full bloom 
 
 Brown 25 10 1 36 
 
 White 00000 
 
 Brown 24 82 79 35 220 
 
 White 3 9 1 13 
 
 Total 52 101 80 36 269 
 
 1937: 78 days after full bloom 
 
 Brown 14 5 76 95 
 
 White 10 5 15 
 
 Brown 33 36 387 456 
 
 White 24 7 1 32 
 
 Total 81 53 464 598 
 
 1938: 90 days after full bloom 
 
 Brown 13 13 
 
 White 11002 
 
 Brown 23 59 16 6 104 
 
 White 15 26 4 45 
 
 Aborted 6 16 30 52 
 
 Total 58 102 50 6 216 
 
 I 
 
 Total button production in these three years 
 
 191 256 130 506 1 083 
 
 of these buttons even fell into the large-size group. The seed-coat 
 remnant in these buttons was larger than that of the suppressed ovule, 
 and from its appearance it seemed that it had ceased enlarging at about 
 the two- or three-week period. Subsequent growth in buttons under 
 these conditions is comparable to that of peaches with frost-killed 
 seeds. 
 
26 BULLETIN No. 458 [October, 
 
 CONTROL MEASURES TESTED 
 
 Experiments carried out with the J. H. Hale in 1929 and 1931 
 to determine whether buttons might be prevented, or at least controlled 
 in part, by cultural methods proved, for the most part, negative. These 
 tests were started before the more detailed studies of the condition in 
 the embryo sac were under way and included pruning, nitrate appli- 
 cations, and pollination. The experiments were limited to these three 
 treatments because any one or all of them could be readily used in 
 the regular cultural program. 
 
 Pruning. The pruning variables set up included a light thinning 
 out of 14-year-old trees at one extreme and a heavy pruning, almost 
 dehorning, at the other. The trees thus treated (Bates orchard) bore 
 a crop in 1929. While the production of buttons on the vigorous 
 growth resulting from the heavy pruning was lighter than in the other 
 type of cutting, the pruning measures did not prevent or appreciably 
 reduce the formation of buttons. This point was tested, it will be 
 noted, during a heavy button year. 
 
 There was also an opportunity in 1929 to check vigor of growth 
 in relation to button production under a wide range of conditions in 
 the state, and no definite relationship with shoot length or vigor of 
 growth was apparent. 
 
 Nitrate Applications. The question arose a number of times as to 
 the possibility of avoiding the production of buttons, at least in part, 
 by increasing the available nitrogen supply during the prebloom 
 period. A fertilizer test was run in the Bates orchard in 1931 to check 
 this point. 
 
 An isolated block with suitable pollinizers some distance away, 
 but with "bouquets" placed in the trees at rather frequent intervals, 
 was divided into plots. On March 6 the following treatment was 
 applied: 20 trees were given 2% pounds of nitrate of soda each; 
 10 trees, 5 pounds each; 40 trees, 10 pounds each; and 10 trees, 15 
 pounds each. The season of 1931 was not a big "button year" in this 
 orchard, but buttons were present in considerable quantities. 
 
 On July 11, after the June drop was over, there were no differences 
 to be seen in the set or in the production of buttons in these different 
 plots. The foliage of the trees receiving the heavier application was, 
 however, deeper in color and the terminal growth was longer. Since the 
 production of buttons was relatively light, the crop was heavy in 1931 
 so heavy, in fact, that the trees had to be thinned. This test was made 
 in the same part of the Bates orchard which produced a heavy button 
 crop in 1929. 
 
7959] 
 
 CAUSE OF "BUTTONS" IN J. H. HALE PEACH 
 
 27 
 
 Pollination Experiments. When this study was started, it seemed 
 advisable to determine what bearing, if any, the source of the pollen 
 might have upon the production of buttons. The first crosses made 
 with this objective in view were made in 1929 in the Bates orchard on 
 J. H. Hale trees which had been heavily pruned the previous year and 
 also on old slower-growing trees. The records of these crosses on the 
 heavily pruned trees and some subsequent crosses as well are given in 
 Table 5. 
 
 TABLE 5. BUTTON PRODUCTION IN CONTROLLED CROSSES 
 
 Cross 
 
 Number of 
 flowers 
 pollinated 
 
 Number of 
 fruits 
 harvested 
 
 Number of 
 buttons 
 
 1929 
 J H. Hale X Perfection Cling 
 
 410 
 
 169 
 
 7 
 
 J. H. Hale X Gage 
 
 788 
 
 204 
 
 7 
 
 J. H. Hale X Gage 
 
 1 380 
 
 50 
 
 1 
 
 J. H. Hale X Elberta 
 
 734 
 
 169 
 
 6 
 
 J H Hale X Elberta 
 
 1 289 
 
 91 
 
 2 
 
 J. H. Hale X Late Elberta 
 
 538 
 
 145 
 
 2 
 
 J. H. Hale X open-pollinated 
 
 1 500 
 
 9 
 
 11 
 
 1933 
 
 78 
 
 10 
 
 
 
 J. H. Hale X Gage (greenhouse) 
 
 106 
 
 51 
 
 
 
 
 115 
 
 46 
 
 
 
 J. H. Hale X Gage (greenhouse) 
 
 50 
 
 35 
 
 
 
 J. H. Hale X Gage (greenhouse) 
 
 273 
 
 34 
 
 
 
 
 407 
 
 72 
 
 
 
 1937 
 Halehaven X unknown 
 
 Whole tree 
 
 73 
 
 21 
 
 Unknown X Halehaven 
 
 4-yr.-old tree 
 
 28 
 
 20 
 
 
 
 
 
 Three things are of importance in this connection in Table 5. 
 
 First, buttons were produced by J. H. Hale in 1929 when pollinated 
 by three different varieties. Buttons were also produced when flowers 
 were emasculated but open-pollinated. Since it seemed at this time 
 that pollination might be an important factor in button production, bee 
 activity was studied in the Bates orchard on trees adjacent to a row 
 of Perfection cling. Hives of bees were placed at frequent intervals 
 along the row. Thus located, the bees had ready access to Perfection 
 cling, which produced pollen in abundance. They worked actively on 
 this variety under very favorable flying conditions, but they worked 
 very little on the J. H. Hale trees adjacent to the hives. They seemed 
 to distinguish readily between the two, since pollen was available from 
 one but not the other. 
 
 Second, buttons were produced in relatively large numbers in the 
 two crosses in which Halehaven was included. This suggests the 
 possibility of a hereditary factor having some bearing upon button 
 production. 
 
28 BULLETIN No. 458 [October, 
 
 Third, it is especially significant that buttons were not produced on 
 any one of the six trees used in the greenhouse crosses pollinated 
 with Gage pollen. 
 
 GENERAL DISCUSSION OF THE PROBLEM 
 
 Necessary Steps in Early Fruit Development 
 
 The growth and enlargement of a peach must be viewed as a 
 series of growth processes which in reality extend from fruit-bud 
 initiation one season to harvest the next. Looked at in this way, the 
 ripe fruit is the end-result of development in those pistils in which 
 all of the necessary steps have taken place normally in that part of the 
 cycle between bloom and maturity. Three growth periods are now 
 generally recognized in this part of the cycle. If a peach is to complete 
 all three of these, it must pass thru three critical stages in the first 
 period: 
 
 1. Complete development in the peach flower at full bloom may 
 be taken as the first critical stage. From the standpoint of fruit 
 setting, this includes a perfectly formed stigma, receptiveness, and an 
 embryo sac with typically the full nuclear content of eight. If for 
 any reason growth is suppressed short of this, fertilization probably 
 cannot take place and the pistils or flowers are cut off at the first 
 drop, thus definitely eliminating them from that group which later 
 form buttons. 
 
 2. If pistil development is normal up to full bloom and all of the 
 nuclei in the sac are functioning, the next necessary step in the con- 
 tinuance of growth is pollination and fertilization. A number of self- 
 pollination tests with the J. H. Hale variety at this Station verify 
 the results of Conners 3 * in New Jersey in showing that nonpollinated, 
 and hence nonfertilized, fruits drop. The most vigorous pistils, how- 
 ever, were found to persist for 35 days or so and to lengthen as much 
 as % inch. It may be concluded from these experiments that 
 buttons do not come from nonpollinated or unfertilized pistils. 
 
 3. The next critical stage to be reckoned with is fertilization. 
 As ordinarily understood in the higher plants, this means double 
 fertilization, as a result of which growth is initiated and made pos- 
 sible in both the embryo and the endosperm. While, in the peach, 
 fertilization does not necessarily insure complete development in the 
 fruit, for there is generally a June drop composed of pistils in which 
 there may be both an embryo and endosperm (Detjen 5 - 6 *), neverthe- 
 less fertilization that is, double fertilization is essential for the 
 
1939~\ CAUSE OF "BUTTONS" ix J. H. HALE PEACH 29 
 
 completion of the entire growth cycle in the peach fruit. This being 
 the case, it would seem that something has happened in buttons which 
 falls short of the normal process of double fertilization but which 
 enables the fruit to persist even tho it does not reach full size. 
 
 Growth Stimulus to Fruit From Fertilization 
 
 With the ground thus limited for a discussion of some of the 
 possible causes of buttons, it will be interesting, first, to consider 
 briefly the growth stimulus to the fruit as a whole which comes from 
 fertilization. While there is always some variation to be found in 
 the time the different flowers on a tree open or in their relative size and 
 advancement immediately afterward, a pronounced difference between 
 them comes soon after fertilization. The stimulus from this process, 
 whatever its nature, sets up a differential in the rate of growth so 
 that it is possible soon afterward to select those peaches which may be 
 expected to undergo normal development. The time at or during which 
 this stimulus affects growth is a matter of considerable interest. 
 Fortunately observations made on three occasions two in the progress 
 of this study throw some light upon how early growth may be 
 suppressed in the ovule or seed and still have enlargement continue 
 in the stone and flesh. 
 
 The first incident to be noted occurred in the spring of 1927. On 
 April 22, and in some places on April 23, the temperature fell as low 
 as 26 F. and 27 F. in southern Illinois and northern Kentucky. The 
 period of bloom of the peach in this area ranged from March 7 to 10 
 in the Ohio river area between the two states, to March 20 and April 1 
 farther north in Johnson and Union counties in Illinois. In the J. S. 
 Whitmire orchard near Rosebud, in Pope county, the peaches were 
 about l / 2 inch in length when the freeze came. This was 30 to 35 days 
 after full bloom. The ovule at the time was generally slightly less than 
 1/4 inch in length. The approximate stage of development in the embryo 
 and endosperm can be seen by referring to the discussion of Elberta at 
 the 40-day period from bloom (page 19). On account of the varia- 
 tion in development, as expressed in the time of bloom from south to 
 north, the seeds were killed at different sizes, varying from % inch 
 in Union county to % inch in Kentucky. The largest peaches of 
 Elberta toward the southern border of the frost zone in Kentucky 
 were at the time of the freeze about an inch in length. 
 
 This situation was studied rather widely in southern Illinois, and 
 the percentage of Elberta peaches with dead seeds after the June drop 
 was found to vary in different orchards from 15 percent to 30 percent 
 
30 
 
 BULLETIN No. 458 
 
 [October, 
 
 of the crop. Some observations were made also on J. H. Hale, but 
 the studies were confined, for the most part, to Elberta. There was 
 much uncertainty as to just what would happen to those fruits with 
 the dead seeds, so arrangements were made to study the situation 
 from time to time until maturity. 
 
 As the season advanced, most of the peaches with the dead seeds 
 were found to persist (Fig. 5). The stone in these peaches reached 
 nearly full size but hardened a few days later than in the normal 
 peaches. Because the kernel was suppressed, the seed cavity was very 
 much compressed (Fig. 6), and by midseason in many of the stones 
 
 FIG. 5. PEACHES WITH NORMAL SEED AND WITH DEAD SEED 
 The bottom row shows J. H. Hale peaches in which the seeds were killed 
 30 to 35 days after bloom. In the top row are normal peaches. (Natural size.) 
 
19391 
 
 CAUSE OF "BUTTONS" IN J. H. HALE PEACH 
 
 31 
 
 with dead seeds there were varying amounts of gum. Sometimes the 
 stone was "split" in these peaches, but generally it was not. 
 
 The relation between the growth of the fruit and the presence 
 of dead seed is shown by a random sample of 151 peaches collected 
 on June 27 (more than 100 days after bloom) in the Whitmire orchard. 
 These were first divided into two lots according to their size. They 
 
 \ 
 
 FIG. 6. SEED CAVITY OF KILLED SEED AND NORMAL STONED 
 At the left are Elberta peaches after the stone-hardening stage, showing the 
 compressed seed cavity when the seed is killed. The fruits at the right show 
 the normal stone development that takes place when the seed is not killed. 
 (Natural size.) 
 
32 BULLETIN No. 458 [October, 
 
 were then cut open and the seed condition noted. In the group of 
 larger fruits 53 peaches had normal seeds and 53 had dead seeds. 
 In the group of smaller fruits 6 bore normal seeds and in 39 the seeds 
 were killed. The dead seeds were completely dried up but the collapsed 
 seed coats could always be found. This general situation prevailed 
 at harvest, altho the peaches with the dead seeds tended to ripen a 
 few days before the others. Some of the largest fruit, however, be- 
 longed to the dead-seed group. 
 
 The next instance to be noted was the subsequent development of 
 the buttons with aborted seeds in the 1938 collection (Table 4). The 
 seed-coat remnant in these buttons was only % inch or so in length, 
 tho this is considerably larger than the usual remnant of the suppressed 
 ovule. In these buttons the seed seemed to have been killed at an early 
 date probably soon after the time of fertilization yet the growth 
 stimulus from fertilization had taken place. In any event, the buttons 
 with this seed condition persisted and enlarged much the same as the 
 others. The date of the suppression of the ovule in this instance could 
 not be determined definitely; so the size of the seed coat is the best 
 index of the stage reached. 
 
 In addition to these two instances, the observations of W. W. 
 McGill, extension horticulturist at the University of Kentucky, will be 
 of interest. He reports that in the spring of 1938 peaches were in 
 bloom in northern Kentucky about March 23 to 26. A frost came 
 April 11, during which the temperature fell as low as 28 to 30 F. 
 As in the Whitmire orchard instance just cited, the seed was killed in 
 varying percentages of the crop in different orchards in the frost area. 
 In midsummer a large proportion of the peaches with the killed seeds 
 were making an apparently normal growth. This instance places the 
 killing period only 16 days or so after bloom a and very near the time 
 of the division in the zygote nucleus, which, of course, would be after 
 division in the fusion nucleus. 
 
 The above observations are interesting in view of the experi- 
 ments of Tukey 26 * in killing the embryo in growing peaches. He found 
 that when the embryo was killed by boring thru the flesh and stone 
 into it with a small drill as early as the second growth period, there 
 was an "abrupt check in fruit development, shriveling, and abscission." 
 On the other hand, when the embryo was killed in the transitional 
 stage between the second and the third period, the growth rate of 
 
 'Since the above was written, Havis 14 * has reported the results of a freeze 
 in Ohio, about three weeks after bloom, in which the peaches persisted after 
 the seed was killed. 
 
1939] CAUSE OF "BUTTONS" IN J. H. HALE PEACH 33 
 
 the fruit remained about the same for a limited period "but ended 
 with earlier ripening and a failure to reach full size." When still later 
 in the third period the embryo was killed, there was an increase in the 
 growth rate in the flesh but earlier ripening. 
 
 While Tukey's experiments are suggestive in showing something 
 of the relationship between growth in the seed and the flesh, they do 
 not throw much light upon the problem at hand because the stage of 
 development in the seed parts was far beyond that reached in buttons. 
 
 The evidence from the early killing of the ovule and the seed is 
 important in an analysis of the disturbance which terminates in 
 buttons. The fact that both buttons and peaches persist and enlarge 
 after the seed has been killed at an early stage shows that the stimulus 
 to growth comes at an early date, and that when it once occurs its in- 
 fluence upon the structure as a whole extends on to maturity. In the 
 evidence from this angle two items are especially significant. First, 
 in the earliest killing observed in Elberta the ovule had enlarged to 
 about the size reached in buttons, yet growth proceeded in the fruit 
 far beyond the size reached by buttons. Second, the growth rate in 
 buttons is not materially affected by the ovule being eliminated by 
 being killed at an early date. It would seem, in the light of subse- 
 quent events, that there was some essential difference between the 
 buttons and the peaches before the seeds were killed. The mere per- 
 sistence in buttons of either a single or a double ovule after the ap- 
 proximate time of fertilization, tho interesting, is apparently of little 
 consequence in influencing growth. 
 
 Departures From Normal Seed Development 
 
 Consideration should now be given to some of the variations en- 
 countered in the sexual process in plants, in order to evaluate their 
 possible bearing upon the production of buttons in the peach. 
 
 The first variation to be reckoned with is parthenogenesis (reduced 
 or unreduced). This factor can be definitely eliminated from con- 
 sideration, however, because when unpollinated peach pistils are 
 left to develop, as noted above, they persist for only about 40 to 
 50 days at most. Likewise, the production of supernumerary embryos, 
 as in citrus (Swingle 24 *), where there is a budding or growth of the 
 nucellar cells into the embryo sac, which gives rise to embryos which 
 are identical genetically with the seed parent, can be eliminated from 
 consideration. In "seedless fruits" also there are varying types of 
 development in the ovule and carpel parts, resulting in some instances 
 in an edible fruit being formed without seed development. In some of 
 
34 BULLETIN No. 458 [October, 
 
 these cases pollination seems to be necessary to initiate growth, but the 
 extent to which pollen-tube growth only stimulates development has 
 not been ascertained. 
 
 Stimulating agents have been used to induce development in fruits 
 in varying degrees. Recently Gustafson 11 * has shown that in some 
 plants the pollen produces a chloroform-soluble substance which initi- 
 ates growth in the ovary and sometimes causes seedless fruits to 
 develop. In the experiments of Gardner and Marth 10 * abscission was 
 prevented in the holly and development comparable to that in pollinated 
 flowers was stimulated in the pistil parts by spraying them with 
 "growth promoting" substances. Experiments of this kind are in- 
 teresting from the horticultural standpoint because crop production 
 is normally based upon the persistence of fruits after both pollination 
 and fertilization. At the same time, use has been made of some plant 
 forms which develop edible fruits from a more-or-less vegetative 
 growth in the receptacle or ovary wall in the absence not only of 
 fertilization but in some cases pollination as well. 
 
 It would thus appear that the type of development found in buttons 
 does not fall within any of the above classes. 
 
 There is, however, in the work of Nixon 17 ' 18 * and Swingle 25 * an 
 analysis of the pollen-embryo-endosperm relationship to fruit develop- 
 ment in the date, which is suggestive in this connection. Their results 
 show that pollen from different varieties has an influence upon size of 
 fruit, shape of seed, and also time of ripening. Since the effect of the 
 pollen upon fruit development is supposed to be thru the growth and 
 formation of the embryo and the endosperm, the term "metaxenia" 
 was proposed by Swingle in 1926 for the influence these structures 
 exert outside the embryo sac. 
 
 Swingle 23 * says, in speaking of the effect of different pollens upon 
 fruit development in the date, that the simplest hypothesis is that the 
 embryo or the endosperm or both together "constitute a ductless gland 
 apparatus that affects, by secreting hormones, the development of the 
 whole date fruit including tissues belonging morphologically to the 
 mother plant and especially to the thickened ovary walls which consti- 
 tute the edible portion of the date fruit." A similar influence is believed 
 also to come from supernumerary embryos in citrus fruits. It should 
 be noted that Swingle considers that the stimulus may come from 
 either the embryo or the endosperm or both. This situation is some- 
 what different, therefore, from that found in buttons of the peach, 
 for in buttons neither of these structures develops normally. 
 
 This same phenomenon has been studied by Nebel 16 * in the apple. 
 
19391 CAUSE OF "BUTTONS" IN J. H. HALE PEACH 35 
 
 By using the statistical method of analysis, he found slight dissimilari- 
 ties in fruit resulting when one variety was pollinated with certain 
 others. 
 
 In the date and the apple, it should be noted, the differences in the 
 structure as a whole came when both embryo and endosperm were 
 functioning normally, these two fruits differing in this respect from 
 buttons, in which neither embryo nor endosperm is normal. 
 
 Conditions in Embryo Sac of Buttons 
 
 Before commenting upon the condition found in the embryo sac of 
 buttons, it seems desirable to restate the following points which seem 
 basic to an analysis of the situation: (a) unfertilized pistils abscise 
 for the most part at the first and second drops (this category would 
 include, in all probability, those pistils in which there was pollen-tube 
 growth up to entrance of the tube into the embryo sac if gametic 
 fusion did not take place) ; (&) since normal peaches generally bear 
 fully developed seeds, i.e., seeds in which both the embryo and the 
 endosperm complete their growth cycle, it would appear that double 
 fertilization was necessary to initiate this development; (c) the evi- 
 dence from killed seeds in both buttons and peaches shows that a 
 growth stimulus to the fruiting structure as a whole takes place at the 
 time of fertilization, or soon afterward, and that once this stimulus is 
 given, the presence of a normal seed from that time onward is un- 
 necessary for growth in the stone and flesh; (c?) it is assumed in the 
 following discussion that gametic fusion is necessary to initiate 
 division in both the zygote and the endosperm nucleus. 
 
 We may now turn to a brief summary of the condition found in 
 the embryo sac of buttons, as revealed in the more than 600 ovules 
 (Table 1) sectioned for critical examination. Within three weeks or 
 so after bloom, the number of nuclei in the embryo sac were found, 
 for the most part, to be reduced to two probably the zygote and the 
 endosperm nucleus. Then, taking the condition in Elberta as typical, 
 it was found that the time of active division in the endosperm nuclei 
 started about 18 to 20 days after bloom. This is about a week or so 
 ahead of division in the zygote and constitutes the initial step in 
 endosperm formation. 
 
 In buttons, however, the division in the zygote was found to be 
 greatly retarded. In 370 of the 600 ovules reported in Table 1, 
 the endosperm nucleus did not divide. If gametic fusion is necessary 
 to initiate division in this nucleus, the interpretation is that in this 
 group fertilization was limited to the egg. The 98 ovules in which the 
 
36 BULLETIN No. 458 [October, 
 
 fusion nucleus was absorbed probably belong to this same group. 
 This leaves only 79 ovules in the later collections in which varying 
 quantities of endosperm nuclei or cells were present. In these, on the 
 above basis, it would appear that gametic union had taken place with 
 the fusion nucleus but not with the egg, otherwise they would have 
 developed into normal peaches. This interpretation, of course, makes 
 it necessary to assume that the fertilization of either the egg or fusion 
 nucleus is equally effective and comparable in inducing growth in 
 buttons. The validity of this interpretation can now be followed in 
 the other types of development found in the embryo sac. 
 
 With the above condition in the fusion nucleus in mind, it is sig- 
 nificant to find that in a total of 480 ovules (Table 1) the zygote did 
 not divide. Since this number corresponds so closely to the 468 ovules 
 in which the endosperm nucleus did not divide or in which it was 
 absorbed, it would seem that division in the zygote is dependent upon 
 division in the endosperm nucleus. This is an especially important 
 point in interpreting the condition found because (a) division in the 
 endosperm nucleus normally precedes that in the zygote, and (b) un- 
 fertilized pistils drop. A zygote could not be found in 28 ovules 
 in the late collections, so it is probable that in these it had either 
 been absorbed or lost in sectioning and staining the material. An 
 embryo was found in only 18 ovules 16 of which were in the early 
 collections before buttons could be selected with certainty. In the two 
 remaining ovules there was no endosperm present at the 80-day period. 
 An early degeneration or absorption of the endosperm in these ovules 
 after the initial divisions seems probable. 
 
 It would seem then, in the light of the above analysis, that single 
 fertilization, i.e., fertilization of either the egg or the fusion nucleus, 
 is the most probable explanation of buttons. Thus, limited in the 
 normal growth stimulus that comes from double fertilization, the fruit 
 persists but enlarges only partially. The interdependence of the embryo 
 and the endosperm is shown, first, by the failure of the zygote to 
 divide when division in the endosperm nucleus does not occur; 
 second, by the failure of the embryo (which normally remains very 
 small until well into the second growth period) to enlarge without 
 endosperm development ; and finally, endosperm growth does not 
 appear to proceed far when the egg is not fertilized. 
 
 Most Probable Cause of Buttons 
 
 Since button production seems to be so definitely related to periods 
 of low temperature following bloom, considerable interest now centers 
 
1939] CAUSE OF "BUTTONS" IN J. H. HALE PEACH 37 
 
 around some of the possible departures from the normal procedure in 
 double fertilization which may be affected by retarded growth or 
 delay. There may be irregularities in the production of gametes, since 
 pollen transfer is light at best when there is unfavorable weather for 
 pollination. Pollen-tube growth would be retarded by low tempera- 
 tures, which alone could result in delayed fertilization. If division in 
 the generative nucleus was prevented or made irregular, so that one 
 of the gametes could not function, there would, of course, be in each 
 tube only one nucleus with gametic potentialities. A possible situation 
 could also arise in delayed fertilization in which the fusion nucleus 
 would be involved in the absorptive process, like the antipodals and 
 synergids, to such an extent that union with the second male gamete 
 could not take place. At low temperature levels all of the processes 
 of fertilization may be so delayed that a considerable period may elapse 
 between the time the egg and fusion nucleus are fertilized. This may 
 set up irregularities in development, since there appears to be such 
 a high degree of interdependence between the zygote (or embryo) and 
 the endosperm. The relatively high proportion of sacs in the 1929 
 collection (Table 1, line 2) with only one nucleus in the sac would be 
 suggestive if there were not such a preponderance of sacs with two 
 nuclei later on, indicating the disposal of the one-nucleus sacs in the 
 first two drops. 
 
 There are still other possibilities to reckon with. Single fertilization 
 could take place in both ovules. This possibility is reflected in the 
 nearly equal development in the two ovules in the double seeds which 
 occur in such a high proportion of buttons. In this case, the egg may 
 be fertilized in both ovules, the fusion nucleus in both, or the egg in 
 one and the fusion nucleus in the other. In any event, a "double 
 dose" of the growth stimulus from the two ovules does not seem to 
 increase the size of the button. Fertilization may also be affected by 
 prolonged cold weather thru irregularities in the division of the 
 embryo-sac nuclei. Irregularities in chromosome distribution in some 
 of the divisions observed in these nuclei could easily result in lethal 
 combinations. Some of the nuclei could, of course, be killed, as is 
 suggested in some of the instances of extensive button production. 
 This possibility must be noted particularly in the case of the egg or 
 zygote, since the latter failed to divide in such large numbers. It is 
 probable, however, that delay in gametic fusion may be equally serious 
 from the standpoint of suppression, especially in the fusion nucleus, 
 since in unfertilized pistils it tends to be absorbed next after the 
 antipodals and synergids. Then, too, there is the possibility of a 
 
38 BULLETIN No. 458 [October, 
 
 nucleus being restored, if division has been long delayed, when the 
 temperature rises rapidly. Furthermore, nutritional disturbances, 
 especially in the nitrogen supply, may tend to aggravate the serious- 
 ness of some of the above factors. 
 
 It will be appreciated, of course, that it is difficult to check some 
 of the variables discussed above because buttons cannot be selected 
 with certainty until the second growth period, which starts 45 days 
 or so after bloom. For that reason increased importance is attached 
 to the persistence of the structures in the ovule. In the light of normal 
 development the antecedents of the condition found can be fairly 
 definitely postulated. 
 
 While, as is apparent from this analysis, there is difficulty in 
 stating definitely just what happened to the early stages of the 2n 
 generation to produce this result, yet since it is the unfertilized pistils 
 that drop, the facts warrant placing the difficulty at this point in the 
 growth cycle. This discussion has therefore centered around the idea 
 of a growth stimulus coming to buttons from the fertilization phe- 
 nomenon single fertilization in this instance. Any condition which 
 would prevent the initial division in the zygote or the endosperm 
 nucleus would influence the growth of the fruit as a whole because 
 complete development in the peach normally includes a seed. The 
 dependence of the zygote upon the endosperm, and vice versa, has 
 therefore been emphasized. 
 
 Finally the question may very well be raised as to why button 
 production is so extensive in the J. H. Hale variety. There is no 
 evident answer to this question in the present approach ; but this 
 variety has one characteristic that is suggestive of an explanation in 
 light of the possible effect of low-temperature periods upon the 
 processes involved in the set, and that is that it is pollen-sterile, or at 
 least nearly so. At best, this characteristic would result in a light 
 transfer of pollen, for bees do not "work" on this variety if they are 
 after pollen, especially if other varieties are near. Sections of pistils 
 collected at random at full bloom show a surprisingly light pollination 
 when conditions are favorable for bee and other insect flight. Light 
 pollination would tend to reduce the chances of favorable genetic 
 combinations taking place at fertilization, compared with other 
 varieties, especially if division in the generative nucleus was affected 
 by low temperatures. 
 
 Under normal conditions there is much variation in the develop- 
 ment found in the embryo and endosperm at midseason, as shown 
 in Fig. 7, which illustrates a range from double seeds to a suppressed 
 
1939} 
 
 CAUSE OF "BUTTONS" IN J. H. HALE PEACH 
 
 39 
 
 FIG. 7. VARIATION IN DEVELOPMENT OF SEED IN J. H. HALE PEACHES, 1931 
 
 Under normal conditions these seeds would all have been approximately the 
 same size. Note double seeds in the first row, the variation in the endosperm- 
 nucleus relationship in the second, and in the last two rows the endosperm- 
 embryo relationship. (Natural size.) 
 
 embryo. That there is considerable difference in the extent of growth 
 in both the endosperm and the embryo at a given period is evident in 
 the two lower rows, where the embryo and its respective endosperm 
 are shown separated. A similar variation is shown in the endosperm- 
 nucleus relationship indicated in the second row of seeds. In Fig. 8 is 
 shown the variations found in the size of buttons on seedling trees 
 during the season of 1939. 
 
 It will be seen from the general trend of this analysis of the button 
 problem in the peach, that emphasis has been placed upon the bearing 
 which unfavorable weather has on gametic fusion rather than upon 
 injury to the vascular conducting tissue, as has been suggested by 
 Harrold and Blake. The type of disorder found in the chalazal region 
 
40 
 
 BULLETIN No. 458 
 
 [October, 
 
 FIG. 8. BUTTONS FROM SEEDLING TREES AT HARVEST TIME 
 BUT BEFORE FINAL SWELL 
 
 Each button is from a different tree and was selected as typical of that 
 particular tree. 
 
 of the seed coats would thus be a consequence of suppressed growth 
 rather than its cause. Furthermore, a study of the vascular tissue of 
 buttons did not reveal any abnormalities in the strands leading to the 
 embryo except possibly in size or diameter. However, the final swell 
 in buttons indicates that the vascular bundles leading to the flesh 
 function much the same as in normal peaches. 
 
1939~\ CAUSE OF "BUTTONS" IN J. H. HALE PEACH 41 
 
 SUMMARY AND CONCLUSIONS 
 
 1. A variable proportion of small retarded peaches called 
 "buttons" is formed in the J. H. Hale variety. Some seasons fruits 
 of this type constitute as much as 90 percent or more of the crop. 
 While this variety produces buttons in greater quantities than other 
 varieties, it is not the only one with this characteristic. 
 
 2. Compared with normal peaches, buttons show the following 
 characteristics: (a) they survive all three of the drops; (6) they 
 fall behind normal peaches in the rate of enlargement during the first 
 growth period ; ( c ) the stone is greatly reduced in size and hardens a 
 little later than in normal peaches; (d) they ripen later than the other 
 part of the crop and sometimes reach a surprisingly large size. 
 
 3. In normal peaches division in the endosperm nucleus occurs 
 about 20 days after full bloom, and in the zygote a week or so later. 
 In buttons, on the other hand, development in the embryo and endo- 
 sperm is either completely suppressed or, if it occurs at all, it is greatly 
 retarded. 
 
 4. In light of the condition found in the embryo sac of buttons 
 at a time when growth had progressed far enough to separate fruits 
 of this type from those which fall at the June drop and from normal 
 peaches, single fertilization seems to be the most probable cause of this 
 condition. The term "single fertilization" is used in this instance to 
 apply to gametic fusion with either the egg or the fusion nucleus. 
 
 5. J. H. Hale and a few other varieties are inherently sensitive 
 to adverse weather during the critical growth stages centering around 
 pollination and fertilization. The retardation of the growth processes, 
 or the light pollen transfer when the weather is unfavorable, seems to 
 be an important factor in the production of buttons. For this reason 
 corrective measures are difficult to apply. 
 
 6. This study shows three distinct levels (to use the terminology 
 of Sinnott 21 *), in the growth and development of the fruit of the peach, 
 which can be related to the phenomenon of fertilization: first, the 
 persistence and development of the pistil, in the absence of fertiliza- 
 tion, up to a fairly definite limit but no further; second, the re- 
 tarded growth of the fruit in buttons, which seems to be associated 
 with single fertilization; third, normal fruit growth and enlargement 
 following double fertilization. 
 
 7. The fact that the fruit grows after the seed or the ovule is 
 killed by freezing places the initiation of the growth stimulus to the 
 fruit as a whole, which comes from fertilization, at or soon after 
 gametic fusion. Once this stimulus is given to the fruit, its enlargement 
 
42 BULLETIN No. 458 [October, 
 
 continues without the seed, resulting in the different growth levels 
 noted above. This stimulus seems to be fractionated in single fertiliza- 
 tion, as contrasted with the stimulus that results from double 
 fertilization. 
 
 8. Restricted commercial plantings are recommended for peach 
 varieties showing a tendency to produce buttons with any great degree 
 of regularity. 
 
1939~\ CAUSE OF "BUTTONS" IN J. H. HALE PEACH 43 
 
 LITERATURE CITED 
 
 1. BLAKE, M. A., et al. Report of the Division of Horticulture. N. J. Agr. Exp. 
 
 Sta. Ann. Rpt. 43, p. 80. 1922. 
 
 2. CONNERS, C. H. Peach breeding, a summary of results. Am. Soc. Hort. Sci. 
 
 Proc. 19, 108-115. 1922. 
 
 3. . Fruit setting in the J. H. Hale peach. N. J. Agr. Exp. Sta. Ann. 
 
 Rpt. 43, pp. 102-104. 1922. 
 
 4. CULPEPPER, C. W., and CALDWELL, J. S. The canning quality of certain com- 
 
 mercially important eastern peaches. U. S. Dept. Agr. Tech. Bui. 196, 
 pp. 1-46. 1930. 
 
 5. DETJEN, L. R. Physiological dropping of fruits. Del. Agr. Exp. Sta. Bui. 143, 
 
 pp. 1-46. 1926. 
 
 6. and GRAY, G. F. Physiological dropping of fruits. Del. Agr. Exp. 
 
 Sta. Bui. 157, pp. 1-38. 1928. 
 
 7. DORSEY, M. J. A study of sterility in the plum. Genetics 4, 417-488. 1919. 
 
 8. and McMuNN, R. L. The development of the peach seed in rela- 
 
 tion to thinning. Am. Soc. Hort. Sci. Proc. 23, 402-414. 1926. 
 
 9. . Fruitfulness of the J. H. Hale peach. Fruits and Gardens, 
 
 March 1928, pp. 6-7. 
 
 10. GARDNER, F. E., and MARTH, P. C. Parthenocarpic fruits induced by spray- 
 
 ing with growth promoting compounds. Bot. Gaz. 99, 184-195. 1937. 
 
 11. GUSTAFSON, F. G. Parthenocarpy induced by pollen extracts. Am. Jour. Bot. 
 
 24, 102-107. 1937. 
 
 12. HALE, J. H. Peach growing in America and the story of the J. H. Hale 
 
 peach. Catalog of Wm. P. Stark Nursery Co., 1914, pp. 48-55. 
 
 13. HARROLD, T. J. Comparative study of the developing and aborting fruits of 
 
 Primus Persica. Bot. Gaz. 96, 505-520. 1935. 
 
 14. HAVIS, LEON. Seedless peaches as a result of freezing injury. Ohio Agr. 
 
 Exp. Sta. Bimo. Bui. 13, pp. 214-219. 1938. 
 
 15. HEISTER, GABRIEL. The cause of little peaches. Country Gentleman 63, 928. 
 
 1898. 
 
 16. NEBEL, B. R. Xenia and metaxenia in apples. N. Y. (Geneva) Agr. Exp. 
 
 Sta. Tech. Bui. 170, pp. 1-16. 1930. 
 
 17. NIXON, R. W. The direct effect of pollen on the fruit of the date palm. 
 
 Jour. Agr. Res. 36, 97-128. 1928. 
 
 18. . The immediate influence of pollen on the size and time of ripen- 
 
 ing of the fruit of the date palm. Jour. Heredity 19, 240-254. 1928. 
 
 19. PALMER, E. F. Ont. Dept. Agr. Hort. Exp. Sta. Rpt., 1919, p. 43. 
 
 20. PECHOUTRE, F. Contribution a I'etude de developpment de 1'ovule et de la 
 
 graine des Rosacees. Annales Sci. Nat. 16, Ser. 8, 1-158. 1902. 
 
 21. SINNOTT, E. W. The cell and the problem of organization. Science 89, 41-46. 
 
 1939. 
 
 22. STEWART, F. C., and EUSTACE, H. J. Imperfect fertilization and the little 
 
 peach. N. Y. (Geneva) Agr. Exp. Sta. Bui. 200. pp. 89-93. 1901. 
 
 23. SWINGLE, W. T. Meta-zenia or the influence of the male parent on the tis- 
 
 sues of the mother plant outside of the embryo and endosperm, especially 
 as exemplified in the date palm. Third Pan Pacific Sci. Cong. (1926) 
 Proc. 1, 1164-1165. Tokio, 1928. 
 
 24. . Seed production in sterile citrus hybrids its scientific explana- 
 
 tion and practical significance. N. Y. Hort. Soc. Alem. 3, 19-21. 1927. 
 
 25. . Metaxenia in the date palm. Jour. Heredity 19, 257-268. 1928. 
 
 26. TUKEY, H. B. Development of cherry and peach fruits as affected by 
 
 destruction of the embryo. Bot. Gaz. 98, 1-24. 1936. 
 
UNIVERSITY OF ILLINOIS-URBANA