132 



The Journal of Heredity 



ears instead of six and twenty-four, 

 as was actually the case. This is not 

 an especially close approximation to 

 theory, although the deviation (4) is 

 only 2.3 as large as the probable error. 



Some of the individual ears that seg- 

 regated for the two kernel types exhibit 

 considerable deviation from a 3:1 ratio. 

 This was noticeably true of the poorer 

 ears which always seemed to possess 

 less than twenty-five per cent, defec- 

 tive kernels. The better developed 

 ears, those with the larger number of 

 kernels, do not depart very greatly 

 from the expected 3:1 proportion, al- 

 though there is still a slight deficiency 

 of the defective kernels. The total of 

 all the ears approaches a 3:1 ratio, but 

 in this case the deficiency of defective 

 kernels in the poorly developed ears is 

 magnified. However, the totals are 

 not entirely beyond the limits of a 

 simple, single-factor hypothesis. 



The seedling data from the thirty 

 self-pollinated ears show one or two 

 points of interest. In the first place, 

 all the ears that were normal in endo- 

 sperm (total of six) produced not a 

 single white seedling. This fact is a 

 strong indication that there is a com- 

 plete association, correlation, or link- 

 age between green seedlings and nor- 

 mal endosperm (or white seedlings 

 and defective endosperm). Otherwise 

 we might expect occasionally a normal 

 ear to produce three green to one 

 white seedling, as was the case in the 

 original grand-i)arental stock. 



The seedling progenies from the 

 twenty-four ears that possessed both 

 normal and defective kernels exhibit 

 some interesting facts (Table IV). In 

 every case the normal grains from 

 such ears were planted separately from 

 the defective ones. The percentage of 

 germination of the latter was very 

 poor. A noteworthy fact is that the 

 second generation ])rogenies (pedigree 

 numbers 4122, 5009 and 5010) showed 

 a far smaller per cent, of germination 



than the original ear and the first 

 generation from it (3354). The rea- 

 son for this is unquestionably due to 

 the fact that the mother ears of the 

 second generation were those chosen 

 because of the distinctness of their de- 

 fective kernels. This means that a 

 smaller defective kernel type was se- 

 lected, which gave a progenv that re- 

 produced this characteristic, thereby 

 possessing less endosperm and less 

 ability to germinate. 



A glance at Table IV shows at once 

 that the seedlings coming from normal 

 grains of heterozygous ears were 

 green in the great majority of cases. 

 Conversely those coming from de- 

 fective seeds were white, with a few 

 exceptions. 



In the first generation from the 

 original ear a greater number of ex- 

 ceptions occur than in the second gen- 

 eration (pedigree numbers 5009 and 

 5010 especially). For this reason it is 

 logical to suppose that the exceptions 

 noted can most easily be attributed to 

 mistakes in classifying the grains into 

 normal and defective. Where this 

 classification is more distinct, as is the 

 case in later progenies (5009 and 

 5010), the exceptions are very rare. 

 Accordingly it seems plausible that the 

 so-called exceptions are not due to 

 genetic crossovers of the linkage be- 

 tween the chlorophyll and endosperm 

 factors involved. This may be a case 

 of a very close but not complete link- 

 age, although that does not seem very 

 reasonable. 



These two types of abnormal ker- 

 nels, the sweet-defective and flint- 

 defective, are distinctly different from 

 the abortive type reported several 

 years ago.' In the abortive type there 

 is a complete failure of endosperm de- 

 velopment. Both the defective and 

 abortive types have been found in 

 several inbred strains of dent corn. 

 Apparently these are similar to those 

 reported by Jones." There appear to 



^ LiNDSTROM, E. W. Chlorophyll Factors of Maize. Journal of Heredity, 11 :269-277. 

 1920. 



^ Jones, D. F. Heritable Characters of Maize, IV. A Lethal Factor — Defective Seeds. 

 Journal of Hcrcditv, 11:161-167. 1920. 



