Digitized by the Internet Archive in 2011 with funding from LYRASIS members and Sloan Foundation http://www.archive.org/details/furtherexperimenOOhaye I'A^g'. 2. \^g 1 CTir P- THE CONNECTICUT AGRICULTURAL EXPERIMENT STATION NEW HAVEN, CONN. BULLETIN 188, SEPTEMBER, 1915 FURTHER EXPERIMENTS ON INHERITANCE IN MAIZE BY H. K. HAYES and E. M. EAST. CONNECTICUT AGRICULTURAL EXPERIMENT STATION. OFFICERS AND STAFF. BOARD OF CONTROL His Excellenc}^ Marcus H. Holcomb, e.v-officio, President. Prof. H. W. Conn, Vice President Middletown George A. Hopson, Secretary Wallingford E. H. Jenkins, Director and Treasurer New Haven Joseph W. Alsop Avon Wilson H. Lee Orange Frank H. Stadtmueller Elmwood James H. Webb Hamden Administration, E. H. Jenkins, Ph.D., Director and Treasurer. ' Miss V. E. Cole, Libra: ian and Stenographer. Miss L. M. Brautlecht, Boolxkeeper and Stenographer. William Veitch^ In charge of Buildings and Grounds. Chemistry. Analytical Laboratory. John Phillips Street, M.S.-, Chemist in Charge. E. Monroe Bailey, Ph.D., C. B. Morison, B.S. C. E. Shepard. G. L. Davis. Assistants. Hugo Lange, Laboratory Helper. V. L. Churchill, Sampling Agent. Miss E. B. Whittlesey^ Stenographer. Proteid Researcli. T. B. Osborne, Ph.D., D.Sc, Chemist in Charge. Miss E. L. Ferry, M.S., Assistant. Botanv. G. P. Clinton, Sc.D., Botanist. E. M. Stoddard, B.S., Assistant Botanist. Miss E. B. Whittlesey, Herbarium Assistant. G. E. Grah.^m, General Assistant. Entomology. W. E. Britton, Ph.D., Entomologist ; State Ejitomologist. B. H. Walden, B.Agr., First Assistant. Q. S. LowRY, B.Sc, I. W. Davis, B.Sc. * M. p. Zappe, B.S. ' Miss G. A. Foote, Stenographer. .4ssistants. Forestry. Walter O. Filley, Forester; also State Forester and State Forest Fire Warden. A. E. Moss. J\I.F., Assistant State and Station Forester. Miss E. L. jXverv. Stenographer. Plant Breeding. Donald F. Jones, B.S., Plant Breeder. C. D. Hubbell, Assistant. Vegetable Growing Howard F. FIuder, B.S. FURTHER EXPERIMENTS ON INHERITANCE IN MAIZE. BY H. K. Hayes * and E. M. East. This paper is a report on the inheritance of certain differ- ences in the endosperm of various maize races that have been made the basis of a division into the subspecies cverta, indurata. indentata and amylacea. To these investigations, a genetic study of the shape of seed which characterizes the socaUed rice pop corns is added. The writers take pleasure in acknowledging the efficient aid of Mr. A. F. Schultze, assistant botanist at the Connecticut Agricultural College, and Mr. C. D. Hubbell, assistant at the Connecticut Agricultural Experiment Station, in the consider- able amount of field work involved. MATERIAL AND METHODS. The parental races used in the crosses were self-fertilized for several years before any hybrids were made, and are be- lieved to have been homozygous for the characters studied. The material from which these races originated was described in a previous publication (See East and Hayes, 1911), bui the following additional points regarding it should be noted ; 1. Zea mays evcrta. The pop corns. No. 64. White rice pop. This white pop is one of the lines which has been pro- duced from No. 23, (East & Hayes, 1911). It breeds true to the "rice" type of seed, — sharply pointed where the style * Mr. Hayes resigned January 1, 1914, to take charge of plant breeding work in the Experiment Station and College of Agriculture of the University of Minnesota. The experimental work here reported was carried on at the Connecticut Station as an Adams Fund Project. The Minnesota Experiment Station and the Bussey Institution of Harvard, should be given credit for time spent in the preparation of this paper for publication. 2 CONNECTICUT EXPERIMENT STATION, BULLETIN 188. (silk) was attached, — although there is some variation in the degree to which this character is expressed. The seeds con- tain only very small amounts of soft starch. No. 65. A white, flint-like pop. This is a strain produced from No. 26, of our previous publication. Its seeds resemble those of a typical flint variety in shape, and contain only very small amounts of soft starch. 2. Zea mays indurata. The flint corns. No. 5. Watson's white flint. This variety is a true white flint which developes a red pericarp in full sunlight. The depth of tint which developes naturally is therefore inversely proportional to the thickness of the husk. The seeds contain a larger proportion of corneous starch than many races of flint corn, though less than that shown by the two pop varieties just described. As in all flints, how- ever, there is a small zone of soft starch in the center of the seed. 3. Zea mays indentata. The dent corns. No. 6. Learning dent. This is a vigorous strain of a famous yellow dent. Like all varieties of its group, the soft starch extends over the whole summit of the seeds, yet the layer is thin enough to allow the race to be classified as a smooth dent (i. e. not beaked). 4. Zea mays amylacea. The flour corns. No. 10. White flour. This is a floury race with seeds resembling the average 8 rowed flint in shape. Though the seeds usually contain only floury starch, sometimes an almost imperceptible layer of corn- eous starch developes in the exterior of the endosperm. It seems likely that this variation is an efifect of external condi- tions rather than of gametic impurity. The plantings have always been made from the original seed envelope, and pains have been taken to prevent the mis- placement of seeds. The different families were marked in the field by heavy stakes to which wired tree labels were attached, but to prevent error through their misplacement a planting plan was made each year showing the exact location and the number of hills of each strain. INHERITANCE IN MAIZE. 3 Classification of seeds was made only from hand pollinated ears, although the remaining ears of a selection were always examined, and in the case of those seed characters not immediate- ly affected by pollination, were used in determining the range of variation. The various races were given different numbers as No. 10 flour corn and No. 5 flint corn. A cross between 10 and 5 was then written as 10 x 5 the female parent appearing first. Differ- ent self-pollinated ears obtained from grov\^ing the cross between (10x5) were labeled (10x5)-l, (10 x 5)-2, etc. Later genera- tions were labeled as (10x5) -1-2, (10x5) -1-3, (10x5)-2-4, etc. If the F^ generation was pollinated with pollen from the flint parent, this ear received the label (10x5)-l x (5-2)-8-3, as the case might be. This back cross was planted the following year as (10x5 x5). Thus we had complete records of the parents and ancestry of our various lines. The field technique has been described in previous publica- tions. For convenience the various crosses Avill be considered under special headings. Family (10x5), Flour x Flint. A cross between the floury race No. 10 and flint race No. 5 was made in 1910, the resulting seeds resembling the female parent. As indicated above, the characteristic difference between these races is the amount of soft starch in the seeds. The flint race produces a small quantity of soft starch in the center of the seed, surrounded b}^ a large layer of corneous starch, while the flour race produces only an occasional trace of corneous starch around the exterior of the endosperm. No immediate effect of pollination through double fertilization was expected, as both our own earlier results and those of other investigators (Correns and Lock) were thought to imply that these differences in the starchy character of the endosperm behaved in heredity as if they pertained to the plant rather than to the endosperm. On growing this cross in 1910, however, we were much surprised to find a clear segregation of seeds on each ear. This fact showed that the physical condition of the starch in these races 4 CONNECTICUT EXPERIMENT STATION, BULLETIN 188. was not a maternal character, since in that case we should have expected a uniform population of seeds on the F^^ ears, resembling either the male or female parents or intermediate between them. A classification of the seeds from the ears of .the F^ gen- eration plants, is given in Table 1. Only two classes could be made : corneous seeds like the flint parent, and floury seeds re- sembling the floury parent. There was no difiicvilty in dividing the seeds into these two classes. Of the thirteen ears shown in Table 1, some contained a greater proportion of flint or of floury seeds than others, but all gave close approximations to a 1 to 1 ratio. This being a novel F^ ratio, further experiments were made to find a genetic interpretation of it. TABLE 1. Self-pollinated Ears from the F^ Generation of a Cross Between No. 10 Flour and No. 5 Corneous Flint. Ear Number Corneous Seeds Floury Seeds (10 X 5)-l 145 186 -3 208 142 -4 169 161 -5 156 169 -6 181 166 -7 189 172 -8 175 203 -9 168 165 -10 213 213 -11 209 205 -12 238 237 -13 190 197 -14 252 223 Total 2493 2439 The floury seeds of (TOxo)-T and (10x5)-8 were labeled (10x5)-TS and (10x5)-8S to distinguish them from the cor- neous (flint-like) seeds of the same ears, which were labeled (10x5)-7C and (10x5)-8C respectively. The data from sev- ^ The word hybrid in these discussions is used in a peculiar sense to avoid longer descriptions. It means a cob bearing a population of seeds belonging to more than one phenotype. INHERITANCE IN MAIZE. eral self-fertilized ears obtained by growing the flotny seeds are given in Table 2. Of a total of 11 hand-pollinated ears, 8 were hybrid', and gave 1 to 1 ratios with a total of 748 corneous to 691 floury seeds. The other 3 ears bred true for the floury habit. Of the open field or naturally pollinated ears, 28 were hy- brids and 23 pure floury. This gives a total of 36 hybrids to 26 pure floury, which, considering the number grown, is a rea- sonable approximation of a 1 to 1 ratio. TABLE 2. Self-pollinated Ears Obtained Through Growing Floury Seeds of Ears (10 x 5) -7 and (TO x 5) -8. Ear Number Corneous Seeds Floury Seeds (10 X 5) -7 S-1 108 125 " -7 S-2 76 59 " -7 S-4 162 126 " -7 S-7 58 55 " -8 S-5 100 97 " -8 S-6 53 48 " -8 S-7 91 89 " -8 S-8 100 92 " -8 S-2 Pure Floury " -8 S-3 " " " -8 S-4 .( <( Total in hybrid ears 748 691 Table 3 gives the results of planting the corneous seeds of ears (10x5)-r and (10x5)-8. Of a total of 9 self-fertilized ears, 5 proved to be hybrids and 4 were pure corneous. The ratio of corneous to floury seeds in these 5 hybrid ears was 464 corneous to 482 floury, a close approximation of 1 to 1. Of- the open field ears 38 were corneous and 34 hybrids. Thus in this case the hybrid and the pure corneous ears are clearly in a 1 to 1 ratio. 6 CONNECTICUT EXPERIMENT STATION, BULLETIN 188. TABLE 3. Self-pollinated Ears Obtained Through Growing Corneous Seeds of Ears (10 x 5)-7 and (10 x 5)-8. . Ear Number Corneous Seeds Floury Seeds (10 X 5)-7C-6 -7C-9 -SC-3 -8C-8 -8C-10 30 73 97 191 73 29 101 81 211 60 -7C-5 -7C-8 -8C-5 -8C-6 Pure corneous Total in hybrid ears 464 482 Table -l gives the results of pollinating ears of the F^ plants with pollen from the parental strains No. 10 flour, and No. 5 flint, respectively. Only 1 ear was obtained from the back cross between (10x5) and the No. 10 parent. This ear had 156 corneous and 184 floury seeds. Three ears resulted from crossing plants of (10 x 5) with the flint, or No. 5 parent. These ears showed various ratios of corneous to floury seeds, but the deviations from 1 : 1 ratios were not all in the same direction. Of the total number of seeds in the four ears, 541: were corneous and 543 floury. TABLE 4. Ears of the First Generation Cross of (10 x 5) Pollinated With Pollen From the Pure Parents, No. 10 Flour AND No. 5 Corneous Flint. Ear Number Corneous Seeds Floury Seeds (10 X 5) -13 X (10-3) -14 - 3 X ( 5-3) -1 - 1 X ( 5-3) -3 - 5 X (-5-3) -7 156 102 107 179 184 79 79 201 Total 544 543 INHERITANCE IN MAIZE. 7 Table 5 gives the results obtained from planting floury seeds of ears (10 x 5)-5 x (5-3)-7 and (10 x 5)-l x (5-3)-3 of Table 4. It was expected that such seeds would be hybrids between the corneous and floury types and should therefore give hybrid ratios when grown. The table shows 10 self-pollinated ears which gave a ratio of 1014 corneous to 850 floury seeds. Seventy- nine naturally pollinated ears were all hybrids showing a definite segregation. The corneous seeds of ears (10 x 5) -5 x (5-3) -7 and (10x5)-l x (5-3)-3 were also tested. A total of 13 self- fertilized and 87 open field ears were pure corneous flints like the corneous flint parent, No. 5. TABLE 5. Self-pollinated Ears Obtained From Planting Floury Seeds of Ear (10 x 5) -5 x (5-3) -7 and Ear (10 X 5)-l X (5-3)-3. Ear Number Co rneous Seeds Floury Seeds (10 X 5) X 5-7S-6 102 116 -5 125 137 -1 77 48 -8 126 110 " -2 , 128 106 -7 67 36 (10 X 5) X 5-3S-2 93 58 -8 74 71 -1 126 92 -6 96 76 Total 1014 850 Table 6 gives the results obtained from planting corneous seeds of ears (10x5)-13 x (10-3)-14. As these seeds were as- sumed to be the result of a cross between corneous and floury types, it was to be expected that all resulting ears would show segregation. Five self-fertilized ears evidently came from hybrid seeds as they gave a total ratio of 653 corneous to 620 floury seeds. Of 57 open field ears, 56 came fromi hybrid seeds. One ear which was somewhat immature probably was a pure soft floury ear. This result may be explained by assuming that one floury seed was planted by mistake. 8 CONNECTICUT EXPERIMENT STATION, BULLETIN 188. Of the 7 self-fertilized ears obtained from planting the floury seeds of the cross between (10x5)-13 x (10-3)-14, all were pure floury. Of the open pollinated ears, 11 were unquestion- ably pure floury while 2 indicated segregation. These ears may have come from corneous seeds planted by mistake, althougn it is possible that a few stalks Avere mislabeled at harvesting time, as the stalks bearing the open pollinated ears all were shocked on the same field. TABLE 6. Self-pollinated Ears Obtained From Planting Corneous Seeds of Ear No. (10 x 5) -13 x (10-3) -14. Ear Number Corneous Seeds Floury Seeds (10x5) X10-3-14C-4 137 116 -9 200 172 _7 70 71 -6 73 94 -10 183 167 Total 653 620 Table 7, gives the results of planting seeds of Ear No. (5-3) -20, pure corneous flint, which was pollinated with pollen from F-L generation cross (10 x 5). There was no immediate efl:'ect of the pollen of (10 x 5)-6 upon the pure flint ear (5-3) -20. Of 5 self-fertilized ears obtained from growing this cross, -1 showed segregation, giving a total of 528 corneous to 508 floury seeds, and 1 was pure corneous. Of the open field ears 24 were pure corneous and 34 showed segregation. These results show that the pollen grains carry the factors for corneous and floury starch in the ratio of 1 to 1. Table 8 gives the results of planting seeds of ear (10-3) -13, which was pollinated with pollen from an F^ ear (10 x 5) -14. There was no visible efitect on the endosperm of (10-3)-13 due to crossing. Three of the self-fertilized ears obtained from this cross had a total of 397 corneous to 377 floury seeds; 6 self- fertilized ears were like the floury parent. Of the open field ears, 32 were homoz3'gous floury and 30 were hybrids. INHERITANCE IN MAIZE. y TABLE 7 Self-pollinated Ears Obtained From Planting Corneous Seeds of Ear No. (5-;3)-20 x (10 x 5)-6. Ear Number Corneous Seeds Floury Seeds 5 X (10 X 5) -2 -3 -5 -S -9 116 116 126 170 Pure corneous 113 116 120 159 Total in hybrid ears 528 508 TABLE 8. Self-pollinated Ears Obtained From Planting Floury Seeds of Ear No. (10-3) -13 x ( 10 x 5) -11. Ear Number Corneous Seeds Floury Seeds 10 X (10 X 5)-6 158 156 -7 84 79 -4 155 142 -1 Pure floury -3 -4 .-5 -6 Total in hybrid ears 397 377 Table 9 gives the results of planting the corneous seeds of ( 10 X 5 )-8C-8 and ( 10 x 5)-8S-8. This F3 generation was grown to determine whether a constant splitting into a 1 to 1 ratio in the hybrid ears could be expected. The results show no great deviations from this ratio. On 9 selfed ears showing segrega- tion there were 996 corneous and 951 floury seeds. The total progeny of (10x5)-8C-8 consisted of 12 hybrid ears and 15 corneous ears, while the progeny of (10x5)-8S-8C included 17 hybrid and 10 pure corneous ears. Considering the few individuals grown the data corroborate those of the pre- vious generation. 10 CONNECTICUT EXPERIMENT STATION, BULLETIN 18S. TABLE 9. Self-pollinated Ears Obtained From Planting Corneous Seeds of F, Generation Ears (10 x 5)-8C-8 and (10 X 5)-8S-8. Ear Number Corneous Seeds Floury Seeds (10 X 5)-8C-8C-l 150 116 -3 116 133 -2 Pure corneous -5 11 _7 " -8 " (10 X 5)-SS-8C-l 114 132 -2 96 115 -4 103 98 -5 142 104 -6 114 95 -7 89 101 -8 72 60 -3 Pure corneous Total in hybrid ears 996 954 Table 10 gives the results of planting floury seeds of ears (10 X 5)-8C-8 and (10 x 5)-8S-8. ' In 8 self-pollinated ears there were a total of 966 corneous and 997 floury seeds. Among the progeny of (10 x 5)-8C-8S there were 17 segregating ears and 16 floury ears, while the progeny of (10 x 5)-8S-8S gave a total of 12 segregating and 10 floury ears. The data in these two tables show that the progeny of an ear which is a cross between floury and corneous may be expected to give a ratio in Fo of 1 cor- neous, 2 segregating to 1 floury ear. INHERITANCE IN MAIZE, SUMMARY. .11 TABLE 10. Self-pollinated Ears Obtained From Planting Floury Seeds OF (10 X 5)-8C-8 AND (10 X 5)-8S-8. Ear Number Corneous Seeds Floury Seeds (10 X 5)-SC-SS-l 113 132 -2 157 174 -5 155 150 -6 100 98 -7 150 150 (10 :; 5)-8S-8S-2 98 107 -3 96 100 -4 98 86 -1 -4 (10 X 5)-8C-8S-8 -3 Pure Floury (I Total in hybrid ears •966 997 To test the purity of apparently homozygous segregates the seeds of pure corneous ear (10 x 5)-8C-6 were planted. A total of 63 ears were all pure for the corneous habit. Pure floury ear (10x5)-8S-3 gave a progeny of 78 ears. All were of a similar character and contained seeds which were nearly filled with soft starch. There were traces of corneous matter in some seeds, but under Connecticut conditions the floury parent also produces traces of corneous matter in a few seeds. Summary and Interpretation of Results. In general, no matter which variety was used as the female parent, there was no immediate visible efl:ect of the male parent in the endosperm of crosses between No. 5 flint and No. 10 floury maize. The F^ generation plants produced ears in which there was a clear segregation of corneous and floury seeds in a 1 to 1 ratio. This ratio was unaffected whether the F^ ears were pollinated with pollen from either the pure flint or the pure floury parent. The progeny of a cross between F^ and the flint parent gave a ratio of 1 hybrid ear to 1 pure flint ear. Like- wise the progeny of a cross between F,^ and the floury parent gave a ratio of 1 floury ear to 1 hybrid ear. Seventy-six 12 CONNECTICUT EXPERIMENT STATION, BULLETIN 188. Fo ears produced from a self -fertilized F^ ear of cross (10 x 5), gave a ratio of 1 pure flint ear, 2 hybrid ears and 1 pure floury ear. The flint and the floury ears bred true in later generations. A total of 69 self-fertilized ears showing segregation gave a ratio of 8,803 corneous seeds to 8,562 floury seeds. This is a ratio of 1 to .961 or approximately 1 to 1. The above results prove that the visible endosperm character of a seed shows the potentiality of the female gamete which entered into that particular seed, and that the male gametes have no immediate effect on the endosperm to determine whether they be corneous or floury. Data from later generations, how- ever, show that the pollen grains of plants from hybrid seeds transmit both the corneous and the floury condition, approxi- mately yi carrying a factor for corneous seeds and the other half a factor for floury seeds. Two hypotheses, will explain the facts : either there is no fusion between the female endosperm nucleus and the so-called second male nucleus of the pollen grain, in which case the en- dosperm developes wholly from the endosperm nucleus of the embryo sac and therefore exhibits the gametic character of the egg cell ; or, there is dominance of the condition of the mother. As ordinarily two female polar nuclei unite with a single male nucleus to produce the endosperm it might be expected that this double dose of the female character should predominate over a single dose of the male character, so that by inspection the seeds would be classed as of the mother type. Correns (1901) used the second hypothesis to account for certain results in his study of the inheritance of color in the aleurone cells, where there ap- peared to be a dominance of the maternal condition. Although East and Hayes (1911) were able to show that Correns' assump- tion was unnecessary in the case of aleurone color, the aberrant ratios obtained being due to the interaction of several factors, it does appear to fit the facts in the crosses just described. A cross between a yellow corneous race and a white floury race would show the correct explanation of the results of the floury-flint cross, for if in Fo the ratio of yellow to white was 3 to 1, and of corneous to floury, 1 to 1, it would then be INHERITANCE IN MAIZE. 13 established that there was a fusion of the female polar nuclei with a male generative cell. Emerson suggested that the same test could be made by pollinating ears which were expect- ed to give a 1 to 1 ratio with pollen from a yellow corneous flint. At the time this test was to be made no seeds of the immediate cross between the corneous and floury races were available, but a number of seeds of hybrid ears (10 x 5)-8C-8S-6 were planted and the resulting plants crossed with pollen from a corneous yellow flint known to breed true. Four ears were obtained of a cross between (10 x 5)-8C-8S-6C (the corneous seeds) and the yellow flint. They proved to be yellow corneous flints. Of the naturally pollinated ears obtained from (10 x o)-8C-8S-6C, 13 were pure corneous flints and 18 hybrids. Five ears of (10 X 5)-8C-SS-(3S (the floury seeds) were also pollinated with pollen from the yellow corneous race. All five ears were yellow and four were yellow floury ears. One ear was a definite hy- brid, however, and gave a ratio of 55 floury seeds to 59 cor- neous seeds. Of the open field ears of (10 x 5)-8C-8S-6S, 13 were pure floury and 14 hybrids. The ear which had all yellozv seeds and yet showed a ratio of 55 floury to 59 corneous, seems sufficient evidence for con- cluding that the apparent dominance of the condition of the mother is due to the fact that the endosperm is produced from a union between two female polar nuclei and one male cell. Thus two doses of a flour corn factor dominates one dose of the corneous factor and vice versa. This fact has an important bearing on the multiple factor hypothesis for interpreting the in- heritance of quantitative characters, for it shozvs that a series of factors may have cumulative somatic effects. Family (10x6), Flour x Dent. This cross was made in 1909 between self-fertilized strains of Leaming No. 6 and floury No. 10. An F^ generation was grown in 1910, and an F., generation from the seeds of ¥^ ear (10 x 6)-l was produced in 1911. There was no appreciable effect on the physical condition of the starch in the seeds of No. 10 due to the pollen of No. 6. On the F^ ears the seeds were in- 14 CONNECTICUT EXPERIMENT STATION, BULLETIN 188. termediate between No. 10 and No. 6 in size, and were rather uniformly dented. As regards the appearance of the starch in the seeds, there was definite segregation, but classification was difficult due to the fact that all seeds contained soft starch at the cap and sides and were dented. The seeds of the self-fertiliz- ed F-L and F, ears were all examined carefully against a strong light, however, and were classified as accurately as possible. The results of this classification are given in Table 11. Considerable variation in the ratios on the difi'erent ears is exhibited, but as a rule there is an indication of a 1 to 1 ratio. Although this seed classification may not have been as ac- curate as might be desired owing to the difficulties involved, the division of the total population of F., ears into corneous, hybrid and floury types as shown in Table 12, is exact and serves as a complete corroboration of the theory. Thirty-six ears were classed as pure corneous, eighty as hybrids and thirty-seven as pure floury. This is certainly a close approximation of a 1 :2 :1 ratio. An examination of the F^ ears showed that there was con- siderable range of variation between the different ears which were classed as corneous or floury types. There was a little va- riation among the seeds of the same ear, but this was not greater than could be explained by differences in development due to physiological causes. The pure corneous or pure floury ears, however, diff'ered from each other by a considerable amount, and it seemed likely that some of this variation would be in- herited. Of the ears of Table 11, (10 x 6)-l-13, (10 x 6)-l-3 and (10 X 6) 1-4 bred true to the floury type. The corneous seeds of ear (10 x 6) -1-5 produced 13 hybrid and 17 pure corneous ears, while the floury seeds yielded 19 pure floury and 16 hybrid ears. Corneous ear (10 x G) -1-5-2 was grown the following year and produced dented ears which bore seeds containing a fair proportion of corneous starch. Ears (10 x 6)-l-6, (10 x 6)-l-9, (10 x 6)-l-12 and (10 x 6) -1-14 of Table 11 were grown in 1912. All produced ears hav- ing seeds with a considerable proportion of corneous starch, the progeny of No. (10 x 6)-l-C) and No. (10 x 6) -1-12 having INHERITANCE IN MAIZE. 15 about the same proportion, and of No. (10 x 6j-l-9 and No. (10 X 6) -1-14, having a greater proportion of corneous starch than the dent parent. TABLE 11. Record of Self- Fertilized. Ears of F^ and F, Generation of Cross Between No. 10 and No. 6. Ear Number Corneous Seeds Floury Seeds (10 X 6)- 5 104 75 (10 X 6) -2 159 226 (10 X 6)- L-1 123 48 '-2 157 152 '-3a 199 • 145 '■-4a 307 250 '-5 342 . 208 '-6a 149 94 '-7 199 182 '-8 124 77 '-9a 259 202 '-10 226 196 '-11 212 209 '-12a 182 106 '-13a 107 108 '-14a 42 30 '-15 72 85 '-16 hybrid ear, immature '-6 considerable corneous starch in all seeds '-9 all seeds very cornec )US '-10 some varibility, no s eeds as No. 10 (varia- tion probably du( ; to immaturity) '-11 pure corneous '-12 pure corneous '-14 all seeds very corneo us '-15 pure corneous '-3 as No. 10 ) probably as No. 10 ) proved pure '-4 fi oury in 1913 '-16 " '-17 as No. 10 '-18 " '-19 " '-13 11 '-20 " '-21 Probably as No. 10 '-22 " '-23 (( '-24 (( Total in hybr id ears 2863 2393 16 CONNECTICUT EXPERIMENT STATION, BULLETIN 188. TABLE 12. F, Ears Obtained From Growing Ear (10 x 6)-l. Parent Stock Pure corneous Hybrids Pure Floury [Hand pollinated ears] Dark yellow seeds of (10 x 6)-l Light yellow seeds of ( 10 x 6)-l White seeds of (10 x 6)-l 7 11 7 11 16 16 24 24 . 12 8 8 9 Total 36 80 37 All ears obtained from ear No. (10 x 6) -1-9 selfed had small seeds with traces of dent. On some ears there were merely traces of dent, but other ears showed the dented condition in all seeds. Selections were made to determine whether these varia- tions were inherited. In 1914 a self -fertilized ear which bore seeds with only a few traces of dent was grown, also an ear with all seed dented. The progeny of these ears is given in Table 13. TABLE 13. The Progeny of E.vrs No. (10 x 6) -1-9-1 and (10 x 6) -1-9-2. Progeny Classes. Condition of Parent Ear % seeds dented % seeds dented Few seeds dented No seeds dented Few seeds dented v4 seeds dented 9 11 12 7 14 20 1 3 These results show that little progress was made bv the se- lection. Of the self-fertilized ears obtained from ear No. (10 x 6) -1-14, one showed no trace of dent, all of the seeds containing a large proportion of corneous starch. This ear was grown and compared with another self-fertilized ear which showed traces of dent in nearly all seeds. The results are given in Table 14. INHERITANCE IN MAIZE, CONCLUSIONS. li TABLE U. The Progenv of Ears No. (10 x 6) -1-14-1 and (10 x 6) -1-14-2. Progeny Classes Condition of Parent Ear V2 Seeds dented Few seeds dented No seeds dented No seeds dented Half seeds dented 5 4 11 37 19 In this case there seems to be some effect of selection, al- though the number of individuals grown is not very large. Conclusions. There seems to be a close agreement between the results of the cross between 10 and 6 and those reported for the cross l)e- tween 10 and 5. It was^ however, more difficult to classify the seeds in the (10 x 6) cross as in No. 6 corneous starch is pro- duced only on the sides of the seed, the cap and the immediate vicinity of the embryo being filled with soft starch. The essential dift'erence between No. 10 and No. 6 in type of starch produced is evidently one factor, yet since different F.. families showed variations in the amount of corneous starch pro- duced, there must be several minor factors which modify its development. There is good evidence that at least some of these minor factors are factors which have a direct eff'ect on totally different tissues. For example, the size and shape of the seed which is at least partly controlled by the type of pericarp (a maternal character ) has considerable influence upon the appear- ance of the starch. To put the matter roughly, in plants which fundamental!}' have the same zygotic possibilities as regards the type of starch in the endosperm, the amount of soft starch ac- tually developed is directly proportional to the size of the seed. Family (10 x 64), Floury x Rice Pop (Very Corneous.) The No. 10 parent had been self-fertilized for three years and the No. 64 parent had been self-fertilized for two years prior to 1909 when the cross was made. There was no visibl^i eft'ect of the pollen of No. 64 on No. 10. F^ ears were grown in 18 CONNECTICUT EXPERIMENT STATION, BULLETIN 188. 1910, but in no case was there a clear segregation among the seeds like that occurring in the F^ ears of crosses (10 x 5) and (10 X 6). This may have been due to the fact that the ears were somewhat immature. The seeds of three F^ ears were separated into two classes ; first, seeds as floury as No. 10 ; second, all re- maining seeds. These partially corneous seeds showed a range of variation from very corneous seeds to those which contained only a little more corneous matter than the No. 10 flour parent. The result of this classification is shown in Table 15. TABLE 15. F;^ Ears of Cross Between (10 x 61). Ear Number Floury Seeds Corneous Seeds (10 X 64) -7 (10 X 64)-10 (10 X 64) -12 93 82 168 216 349 353 Total 343 918 The seeds of (10 x 64) -7 and (10 x 64) -10 were planted in 1911. Those which had been classed as of the floury type like No; 10 were planted as (10 x 64) -7S and (10 x 64)-10S. The remainder of the seeds of the same ears were planted as (10 x 64) -TC and (10 x 64) -IOC respectively. The results obtained from a classification of the progeny of these ears are given in Table 16. TABLE 16. Ears Obtained From Planting (10 x 64)-7C and 7S and (10 X 64) -IOC and lOS. Progeny Classes cU lU Parent Type 3 O ^ u '5 '•- edia eous 1- CU u 3 nterm Corn 3 3 ^ C u PM '"' (10 X 64) -7S 4 15 11 6 (10 X 64)-10S 6 13 17 2 (10 X 64)-7C 16 7 13 (10 X 64)-10C 1 15 6 10 INHERITANCE IN MAIZE. 19 There is a similarity in the variabihty of the populations ob- tained from the floury seeds of (TO x 64) -TS and (10 x 64)-10S; the progeny of the corneous seeds of (10 x 64) -10 and (10 x 64) -7 also show about the same percentage of ears in the different classes. Two self-fertilized F^ ears (10 x 64)-10S-5 and (10 x 64) -lOC-4 were classed as definite hybrids. The corneous seeds of these ears gave a range of variation from purely corneous to definitely hybrid ears, there being 3.3 times as many corneous, intermediate, and definitely hybrid ears, as there were pure cor- neous ears. The floury seeds of (10 x 64)-10S-5 and (10 X 64)-10C-4 produced 4.2 as many hybrid and intermediate ears as pure floury ears. Thus these two F^ ears showed as variable a progeny in Fg as had been found in Fo. Five self-fertilized Fg ears of the intermediate floury class from the progeny of (10 x 64)-10S gave a total population of 165 ears ; of which 19 approached pure corneous but contained a larger percentage of soft starch than the corneous parent, 12 ap- proached the floury parent, and 134 were intermediate. Many of these intermediate ears showed some variation among the seeds, but no clear segregation. F, corneous ears, (10 x 64)-10C-9, (10 x 64)-7C-9, and (10 X 64)-7C-l bred true for the corneous habit in Fg. (10 x 64) -lOC-9 was grown in F^ and again bred true. Pure floury ear (10 x 64)-7S-13 bred true in Fg and F^ for the floury habit. One self-pollinated intermediate Fo ear, (10 x 64)-7C-2 proved to be a hybrid and gave in Fg 15 corneous ears, 32 definite- ly hybrid ears showing clear segregation, and 18 intermediate cor- neous ears which showed some variation. This is a 1 :2 :1 ratio. Two F^ ears bred from the intermediate class, (10 x 64) -7C- 2-10 and (10 x 64)-7C-2-l, together produced 14 ears approach- ing pure corneous, 68 intermediate variable ears and 4 approach- ing pure floury. These ears are probably all intermediates, the variation being due to maturity and possibly due to the effect of other inherited factors. Of 3 other F, ears classed as inter- mediate, 2 gave intermediate progeny and 1 proved to be a definite hybrid. Self-pollinated ears of selections (10 x 64)-7S-l and (10 x 64)-7S-7 from the intermediate class were grown the fol- lowing year. These results are given in Table 17. 20 CONNECTICUT EXPERIMENT STATION, BULLETIN 188. TABLE 17'. Progeny of Ears No. (10 x 64)-7S-l and (10 x 64)-7S-7 Which Were Classed As Intermediate Variable Ears. Parent type Classification of Progeny Ear No. c s I .5 P o o < (10 X 64)-7S-l-3 (10 X 64)-7S-l-6 (10 X 64)-7S-7-10 ■' -3 -4 -S Most corneous ear " floury ear Intermediate ear 2 3 3 35 40 35 48 47 t46 1 I Of this population. 25 open field ears were very variable and showed definite segregation. The self-fertilized ears were comparatively uniform. The data in Table IT show that intermediate \ariable ears tend to give intermediate variable progeny. The ears did not all become thoroughly mature, and this may be the explanation of their variable endosperms. There is also the possibility that other heterozygous factors may have influenced development in such a way as to produce variation. (East & Hayes 1911). Eg ear (10 x 64)-10C-l-6 produced intermediate and corneous seeds in a ratio approaching 1:1. The corneous seeds of this ear gave a progeny of 28 purely corneous and 2-1 definitely hybrid ears, while the intermediate seeds gave a progeny of 2 corneoits cars, 17 definite hybrids and 23 intermediate variable ears. This is a close approximation of a 1 :2 :1 ratio. That only 1 factor de- termined whether corneous or intermediate seeds were to be pro- duced in this ear is further indicated by the separation of seeds from five self-pollinated ears which were classed as definite hybrids. The results are given in Table 18. The total number of corneous seeds in these five ears were 514 and of intermediate seeds 491. This clearly approaches a 1 to 1 ratio. INHERITANCE IN MAIZE. SUMMARY. 21 TABLE IS. Classification of Seeds of Hybrid Ears Obtained From Planting Intermediate and Corneous Seeds of Ear (10 X 64)-10C-l-6. Ear Number Corneous Seeds Intermediate Seeds (10 X 64;-lCC-l-6l-2 -9 -8 (10 X 14)-10C-l-6C-8 -10 101 78 80 135 120 84 92 67 124 124 • Total in hybrid ears 514 491 Summary and Interpretation of Results. The pollen of No. 64 pop apparently had no effect on the character of the endosperm of No. 10 flour. This is in agree- ment with the results of the crosses (10 x 5) and (10 x 6). The Fj ears showed the results of segregation, although in this case there was a range of variation from the floury to the corneous type. Seeds of this F^ generation (Fo seeds) produced a popu- lation of ears ranging from the pure corneous to the pure floury type. One uniformly floury ear bred true in Eg and F^^ for the floury habit ; three ears with purely corneous seeds also bred true. Two F, ears (10 x 64)-10S-5 and (TO x 64)-10C-4 gave as variable an Eg progeny as had been found in E,. The ratio in this case was approximately 1 pure corneous ear to 6.2 intermediates and definite hybrids to 0.8 pure floury ears. Other Fo ears gave a 1 :2 :1 ratio in Eg as was the case in the (10 X 5) and (10 x 6) crosses. An example of such a ratio is that obtained from Fo ear (10 x 64)-7C-2, which produced 15 corneous ears, 32 definitely hybrid ears and 18 intermediate ears. Several self-fertilized intermediate F2 ears bred comparative- ly uniformly, giving a progenv which contained more corneous starch than the No. 10 parent but less than the No. 64 parent. Thus intermediate ear (10 x 64)-7S-l produced 41 ears of the intermediate type none being either purely corneous, definitely hybrids, or clearly floury. A self-fertilized ear (10 x 64)-7S-l-2 which contained more corneous starch than other self-fertilized 22 CONNECTICUT EXPERIMENT STATION, BULLETIN 188. ears, yielded a progeny of 35 variable intermediate ears and 2 ears approaching the corneous condition although they were not truly corneous ears like No. Qi. Self-fertilized ear (10 x 64)-7S- 1-6 which approached the floury type, produced 10 intermediate variable ears and 1 ear with somewhat more floury matter, though it did not compare with No. 10. Thus in a total of 119 ears from this intermediate line (10 x 61)-7S-1 there were no pure cor- neous, pure floury or definitely hybrid ears. This variation may largely be due to differences in the maturity of the seeds and ears, as the amount of corneous starch is directly dependent on the maturity of the seeds, although of course the hereditary con- stitution determines the amount which can be produced under favorable conditions, but there is also considerable likelihood that what one may call minor inherited factors modify the expression of the character. Whether more than one major factor affecting the endosperm is involved is still a question. The ratio obtained among the progeny of ears (10 x 61:)-10S-5 and (10 x 61)-10C-4, the facts that certain F2 ears produced an Fg progeny similar to the 10 x 5 cross, and that others bred approximately true to the intermediate, the pure floury, or the pure corneous types might seem to indicate two such factors, but analysis is so difficult that this is only a reasonable guess, as will be shown by a considera- tion of all of the facts. The following conclusions we hold to be justified by the data at hand. 1. The factors directly responsible for the dift'erences in the physical condition of the starch exhibited by the so-called starchy sub-species of maize, the flour, dent, flint and pop corns are as truly endospermal in their inheritance as endosperm color char- acters. They partake of the nature of the embryo and not of the plant on which they are borne. 2. These characters appear superficially to be maternal for the following reasons. The endosperm nuclei are triploid due to the fusion of two nuclei from the female gametophyte with one nucleus from the male gametophyte. In the characters under discussion, the presence of two factors always dominates the presence of one factor. Thus corneous female (CC) x floury male (F) is phenotypically corneous, while floury female (FF) x corneous male (C) is phenotypically floury. These characters. INHERITANCE IN MAIZE. 23 therefore, appear to be inherited in a different manner from endosperm colors where the presence of one color factor is suf- ficient to cause perfect development of color. This is the first proof of a cumulative somatic effect of factors. 3. From the fact that in these crosses, as well as in num- erous others involving the same subspecies of maize that we have examined, the F, reproduces the grandparental and no types more extreme than the grandparental types (with possibly a rare ex- ception), it follows that a large series of multiple allelomorphs affecting the starchy condition of the endosperm exists. 4. From the facts (a) that where no complications such as dift'erences in shape and size of seed exist (viz. cross 10 x 5) segregation is simple and definite, (b) that where such differences in shape and size of seed do exist segregation occurs but is diffi- cult to demonstrate clearly until these complications have been eliminated, it follows that although only the presence of factors in the endosperm affect these characters directly, the maternal zygotic constitution has an indirect effect. This effect is roughly a direct correlation of size of seed with floury condition of the endosperm. Havmg these facts m mmd, let us see what difficulties ob- struct analysis if it be assumed that two factor differences may differentiate the endosperms of certain maize varieties in respect to starch as seemed possible in the case of cross (10 x 64). The simplest assumption would be that each of these factors has a similar eff'ect, and when one sees the difficulties thus in- volved, and considers that such a simple assumption is less prob- able than one in which each factor has a different effect, it is clear why we do not wish to assert dogmatically that two such factors are involved in the cross between the flour and the pop- corn. Let the flour corn be AABB and the pop corn aabb, it being understood that the phenomenon of dominance is in this case wholly a quantitative reaction. The Fj generation in the cross and its reciprocal would be AAa BBb and aaA bbB 24 CONNECTICUT EXPERIMENT STATION, BULLETIN 188. In each case, the predominant influence of the mother would Ije such that any effect of the father would scarcely be noticeable. Four types of gametes would be formed in the F^ generation as usual, AB, Ab, aB and ab, — but the appearance and breeding qualities of the zygotes formed would be peculiar, as is shown in the following table, due to the fact that the "gametes" of the embryo sac are the fusion cells AABB, AAbb, aaBB and aabb. 1 AAABBB 1 1 AAABBb I , ,., , , ,.^ 1 AAaBBB Appear alike breed ditterently 1 AAaBBb j 1 AAAbbB 1 1 AAAbbb [ . ... . 1 A.AabbB Appear alike breed ditterently 1 AAabbb J 1 y Appear alike breed differently 1 aaABBB 1 1 aaABBb 1 aaaBBB 1 aaaBBb J 1 aaAbbB 1 1 aaAbbb , Appear alike breed differently 1 aaabbB I " • 1 aaabbb J The grandparental types haye appeared of course and will breed true, but other indiyiduals will look like the grandparents though they will breed differently and will ultimately giye the whole series if crossed together. Other complications will occur to any one who takes the trouble to study the table. Family (65 x 64), White Pearl Pop x White Rice Pop. In 1910 a cross was made, between white rice pop No. 64 and pearl pop No. 65 for the dual purpose of determining the probable yalue of such a cross for the commercial production of first gen- eration hybrid pop corn, and to study the inheritance of the pointed seed characteristic of the rice pop corns. The F-^ plants were considerably more vigorous than either parent. The seeds produced approached the length of those of the longer type, the white rice pop, and the width of those of the INHERITANCE IN MAIZE. ',i'0 broader parent, the pearl pop. Thus the F. seeds (those borne on F^ plants) were considerably larger than those of either parent, and since the pericarp was weaker rather than stronger than that of the pure tjqies, the}^ did not pop as well. TABLE 19. Inheritance of Seed Shape in a Cross Between White Rice Pop No. 64 and Pearl Pop No. 65. - Parent Type Condition of Progeny Ratio of Pointed ears to intermedi- ate and non point Ear Xumber 147 6 5 9 4 Inter- mediate Point Non Point 64-4 65-8 (65 X 64) Fi (65 X 64) -1 F. " -3 " -5 •' -6 '■ " -1-13 Fo Pure pt. Non pt. Int. pt. Int. or non pt. 132 64 •49 55 58 *21 200 1 5 3 2 1:10.8 1:10.8 1 :6.5 1:15 * Possibly non-point as the point was scarcely perceptible. The data on the cross are given in Table 19. The F^^ gen- eration was of intermediate habit, — there being some projection of the seeds at the point of attachment of the silk. Four selfed F-L ears furnished F^ generations. The progen}^ of these ears was variable, the seeds of some ears being as completely pointed as the white rice pop parent, the seeds of others non-pointed like the pearl pop parent, while the greater number were of various intermediate types. Of a total progeny of 263 individuals, 24 ears were classed as pure pointed like the white rice parent. This is an indication of a 15 :1 ratio, although one can not be cer- tain that the classification was correct because these ears were not selfed and could not be tested by the type of progeny produc- ed. A number of F^ ears were self-pollinated, but none happened to be obtained which could be classed as typically pointed. One 26 CONNECTICUT EXPERIMENT STATION, BULLETIN 188. ear having seeds but slightly pointed (possibly non-pointed) was grown in F,. The twenty-one ears produced were like the parent ear, showing only slight projections on the seeds at the tip of the ear. The difference between the pointed seed characteristic of the white rice pop corn and the normal shape of seed typical of other varieties can not be explained by a single factor. If, however, we assume that there is a difference in two factors, that each factor is allelomorphic to its own absence and is inherited independently of the other, that both are necessary for the production of the pure pointed condition, and that either of them alone may pro- duce a tendency to a pointed condition (intermediate point), the data accord fairly well with the theory. But since on this hypo- thesis it is assumed that a factor in the heterozygous condition, produces only half as great an effect as when homoz3'gous, one can appreciate the difficulty of classifying the ears correctly by in- spection, and since classification must be exact to prove such a case merely by the ratios obtained it must be admitted that our evidence is open to some criticism. On the other hand, we be- lieve that the facts are clear enough to make them of some value in practical plant breeding, and we do not believe that the case is sufficiently important to make it worth while overcoming the difficulties that stand in the way of a more acceptable proof. Furthermore, the data on the next cross appear to corroborate our earlier facts. Family (64 x 6), White Rice Pop x Leaming Dent. This cross was made in 1909 between self-bred Leaming and white rice pop strains. The purpose of this cross was a further study of the mode of inheritance of quantitative differences in seed size, of the proportion of corneous to soft starch, and of the pointed habit of the white rice pop. The results on inheritance of seed shape are given in Table 20. These results again indicate that two factors are involved. Furthermore, examination of Table 20 and Table 21, shows that the pointed character is inherited independently of the position of starch in the seeds. INHERITANCE IN MAIZE. TABLE 20. Inheritance of Seed Shape in a Cross Between No. 6 Leaming Dent and No. 64 White Rice Pop. Parent Type Condition of Progem' Ear Number Pure Inter- Non Point mediate Point Point " 64-4 Pi Pure pt. 147 6-3-4 Pi Dent non pt. 107 6 X 64 Fi 112 (6 X 64) -4 F. Int. pt. 47 65 20 -6 F2 " 35 44 17 -6-6 F3 Pure pt. 26 -6-3 F3 "■ 21 2 -4-8 F3 Pure (?) pt. 44 20 -4-9 F3 41 11 -6-4 F3 Int. pt. 4 44 1 -4-6 F3 " 13 31 -4-4 F3 " 13 , 37 2 -6-5 F3 Non pt. 4 (?) 53 4 -6-7 F3 " 3 34 -4-3 F3 " 2 41 17 -4-7 F3 " 11 45 7 -4-10 Fa " 52 13 -4-5 F3 " 6 37 3 (6 X 64) -6-6-4 F4 Pure pt. 35 -6-6-1 " Pure or int. pt. ( ?) 27a -4-8-8 " Pure pt. 61b K?) -6-3-6 " " 43 -6-5-4 " Int. pt. K?) 38 5 -6-5-3 " K?) 35 11 -6-7-8 " 26 11 -4-8-3 " 16 40 -4-3-7 " 5 72 -4-10-5 F4 47 22 -4-10-3 F4 Non or int. 48 17 -4-3-5 F4 Non 60 a — 4 ears with points not as strongly developed as the remaining ears, b — 1 ear with points not as strongly developed as the remaining ears. The F^ generation was intermediate as regards the pointed Condition, and there was segregation into pointed, non-pointed and intermediate ears in F.,. Thirteen self-polHnated F., ears were grown in F.:,. Of these, the following F., ears were classed as pure pointed, (6 x Gi)-6-6, (6 x 64)-6-3, (6 x 64)-4-8, (6 x 64) -4-9. Two of these ears, (6 x 64) -6-6 and (6 x 64) -6-3, bred true in F^, while (6 x 64)-4-8 and (6 x 64)-4-9 showed segrega- 28 CONNECTICUT EXPERIMENT STATION, BULLETIN 188. tion in F., with a total of 85 pointed and 31 intermediate pointed ears. Tavo self-fertilized ears, (6 x 6-1 J -4-8-8 and (6 x 61) -4-8-3, were grown in 1914. One proved to be a pure pointed ear and the other again gave pure pointed and intermediate pointed seeds. These results might have been obtained if ear (6 x 64) -4-8 were homozygous for one factor for point and heterozygous for a second factor. Three self-fertilized F2 ears of the intermediate class showed a range of variation in F3 from pure pointed to non-pointed ears. Six F2 ears classed as non-pointed Avere proved to have been hybrids by the F3 results. One of these, (6 x 64)-4-T, produced 52 intermediate and 13 non-pointed ears. As no typically pointed ears were obtained it seems fair to conclude that the parent ear (6 X 64) -4-7 was heterozA^gous for 1 factor for pointed seeds. Tavo self -fertilized F3 ears of line (6 x 64) -6-6 Avhich bred true for the pointed habit in F3 Avere groAvn in F^. Ear ( 6 x 64) -6-6-4 gave a progeny of 35 ears, all of Avhich Avere pure pointed : while (6 x 64) -6-6-1 had a progeny of 33 pure pointed ears and 4 Avith points more strongty developed than the intermediate class, but not so strongly developed as the 23 pure pointed ears. This mav be a physiological A'ariation or it may possibly l)e due to chance pollination. As these four were open field ears, it is im- possible to determine the matter by further breeding. The results are an excellent illustration of the old A'ilmorin Isolation Principle, — in modern times the genotype hypothesis. — for they shoAv that the only sure method to determine the breeding value of an ear is to grow and examine its progeny. A part of the pure pointed class gave a pure pointed progeny ; other ears proved to be hybrids. There Avas also considerable difference in the progeny of different intermediate ears ; some being apparently homozygous for one factor for point and heterozygous for another, Avhile others appeared to be heterozygous for a single factor. These results, as did those in the case of the (65 x 64) cross, indicate that two factors are involved in the production of strong- ly pointed maize seeds. Table 21 gives the results of a study of the dented condi- tion and the proportion of corneous to floury starch in the same INHERITANCE IN MAIZE. 2'.) cross. The white rice pop parent contains only a small amount of floury starch, while the dent variety has corneous starch at the sides of the seed and floury starch at the cap and next the em- bryo. There was no effect on the development of the amount of corneous starch in No. 6 dent due to the pollen from No. 64 pop. The F^ generation cross produced ears with intermediate sized seeds. These ears would have to be classed as dents. TABLE 21. Inheritance of Dented Habit and Proportion of Corneous TO Floury Starch. Parent Type Condition of Progeny Ear Number -w _^ T3 ■*>-S -■2 m"^ T3 f; « ?^ M-i ^ A a £ ^l 5 S fe-d i^ 64-4 pop, non-dent 107 6-3-4 dent 147 6 X 64 Fi 112 (6 X 64) -4 Fo nearly pure dent 15 27 27 20 3 -6 " " '• " 38 34 21 8 -4-4 F3 pure dent 29 1 15 5 1 -4-5 " " " 1 11 24 6 -4-8 " " " 39 9 ; -6-6 " " " 24 2 -6-5 " " " 25 19 13 4 -6-7 " nearly pure dent 3 11 15 5 2 -6-4 " " " " 2 2 35 8 2 -4-7 " half seeds dented 14 24 5 3 -4-9 " " " " 30 a 8 2 -4-6 " few seeds slightly dented 12 7 11 14 -6-3 " " " " " 2 2 35 8 2 ' ■ -4-10" non-dented 17 48 -4-3 " " " 26 34 -6-3-6 F4 pure dent 2 5 12 21 2 -6-5-3 " " " 32 1 4 -6-5-4 " " " 6 23 12 3 -6-6-1 " " " 2 3 9 12 1 -6-6-4 " " " 15 14 4 2 -6-7-8 " half seeds dent 1 4 9 23 -4-8-8 " half seeds slightly dent 6 21 16 IS ' -4-8-3 " seeds slightly dent 4 28 12 13 -4-3-7 " few seeds dent 1 8 29 40 -4-3-5 " no seeds dent 5 44 -4-10-5 F4 few traces of dent 5 63 -4-10-3 " non-dent 67 30 CONNECTICUT EXPERIMENT STATION, BULLETIN 188. Two Fi ears (6 x 64) -4 and (6 x 64) -6 were grown in F^. Both populations showed a wide range of variation. The ears were classed as pure dent, nearly pure dent, half seeds dent, few seeds dent and non-dent. Ear (6 x 64) -4 had progeny of each class, while (6 x 64) -6 produced progeny in all classes except the non-dent class. Thirteen F2 ears were grown in F,. Two non- dented ears gave a progeny of non-dented ears and ears with a few seeds slightly dented. No ears bred true in F3 or F^ for the pure dented condition, although some selections gave a progeny with a much larger proportion of dented ears than others. Twelve F3 ears were grown in F4. Ear (6 x 64) -6-5-3 pro- duced the greater proportion of its progeny in the pure dent class. Ear (6 x 64) -4-10-3 bred true to the non-dented character, and the corneous non-pointed condition. Ear (6 x 64) -6-5-3 bore seeds which approached the size of those of the No. 6 Learning parent, although the range of variation was somewhat greater. Ear (6 X 64) -4-8-3 gave a uniform progeny in 1914, and bred comparatively true to the seed size of the pop parent. The seeds of those ears which were classed as non-dents and those with a few seeds dented, popped perfectly whe?n tested. The condition of the other families is shown in the table. Summary and Interpretation of Results. The data from these two crosses indicate strongly that two independently inherited factors are necessary for the production of a strongly pointed seed. The rice pop point can be transferred from the pop parent to dented seeds by crossing and selection ; the inheritance of these characters being entirely independent of each other. A study of the proportionate amount of corneous and floury starch in the 6 x 64 cross shows a wide variation in Fo. One ear (6 X 64) -4-10-3 bred true for about the same amount of corneous starch in F^ as that of the No. 64 parent. Other ears were again as variable as F^, while still others showed a smaller range of variability. It is impossible to state how many factors are in- volved in producing these somatic difl:'erences, but it is a fact that the parental types can be recovered easily and will breed true. inheritance in maize, conclusion. 31 Conclusion. Since a summary of the results obtained for each cross has been given in its proper place, it seems unnecessary to repeat them here. If the reader will refer to them he will find an ab- stract of the paper. Literature Cited. CORRENS, C. 1901. Bastarde zwischen Mai-srassen niit besonderer Be- riicksichtigung der Xenien. Bibliotheca Botanica. 53:1-161. EAST, E. M. and HAYES, H. K. 1911. Inheritance in Maize. Connecticut Expt. Sta. Bull. 167:1-142. EMERSON, R. A. and EAST, E. M. 1913. The Inheritance of Certain Quantitative .Characters in Maize. Nebraska Station Research Bull. 3 :1-130. SHULL, GEORGE HARRISON. 1914. Duplicate Genes for Capsule-form in Bursa bursa- pastoris. Zeitschrift fiir induktive Abstammungs-und Vererbunffslehre XII: 97-149. PLATE I. No. 5, corneous flint at bottom, No. 10 flour at top and Fi at left. The two lower center ears show the result of planting corneous Fi seeds and the two upper center ears show the result of planting floury Fi seed. PLATE II. a. No. 10 flour at left. No. G, Learning dent at right. The four other ears represent the Fs generation of cross. They are uniformly very corneous with sHght traces of dent. The seeds are smaller than those of either parent and of uniform size. h. Average ears of No. 65 pearl pop at left, No. 64 rice pop at right with average Fi in center. The two remaining ears represent the extremes of Fo. PLATE III. a. Xo. G Learning dent at right, No. 64, rice pop at left and immediate cross, (6 X 64), above. The two central ears show the variation in seed size and condition of point of the Fi generation. b. Fs generation of cross (6 x 64). Note the segregation of characters. PLATE 1\' (6XfeV)-V-/0 (6>C6V;-6-J" ^U ('GXfeV)-($-6 Upper row, F3 generation ears, with large amount of corneous starch. Some ears with slight trace of dent. Middle row, average progeny of F2 ear which bore good sized dented seeds. Lower row, average progeny of F2 ear which bore intermediate dented seeds with a well-developed point. PLATE V. t4 (644)-6-6-4 6-64J-4-/0-J (6>^6i)'(,-S-3 (M4M-^-^ Average ears of parental types No. 6, Learning dent and No. 64, white rice pop above. The ears below represent the variation in 4 F4 families. (6 X 64) -6-6-4 bred true for the rice point, (6 x 64) -4-10-3 bred true for corneous, non-dented seeds, (6 x 64) -4-8-8 is a small-seeded selection and (6 X 64) -6-5-3 is a large-seeded selection. (Photo by Walden.) PLATE VI. O0UH)-7S-IZ Oox6V)-/OC-9 Upper row, ¥s generation of cross between Xo. 10 flour and Xo. 64, rice pop, which bred true for the floury habit. Middle row, F3 generation of same cross which bore seeds of intermediate t5'pe. Lower row, F3 generation of same cross which bred true for the corneous habit. PLATE VJ[. Qox(,^)-/OS'(, a. Fs generation of cross between No. 10 and No. 64 which bred true for the seed size of No. 10. b. F., generation of cross between No. 10 and No. 64 which bred true for the seed size of No. 64. The corneous seeds popped perfectly. ^ ^ o n ^ O y n 7 University of Connecticut Libraries 39153029221803