On the Composition of Factorial Formula 



for Zygotes in the Study of Inheritance 



of Seed -Characters of Z<'(i Mtnjs L. 



with Notes on Seed-Pigments. 



By 

 Koiijiro Fnjii ;ui<l Vosliiiiari Kinvada. 



The study of maize b\' crossing experiments was undertaken 

 rather earlj'-, even the fact of the dominance of roundness or 

 yellow colour of maize-seed over its recessive winkledness or 

 white colour having been already recorded in 1876.'^ But it is 

 only since the rediscover}- of Alendelian principles in 1900 that 

 maize has become a common object of demonstrations of Men- 

 deliati inheritance. As the characters presented by this plant 

 are, however, far from being so simple as it seems to be often 

 considered, a thorough analytical examination of genetic factors 

 is required. So it would not be out of place to present here some 

 considerations of the factorial composition concerning this plant. 



The various materials of the maize-seed for study have been 

 sot from the culture made bv one of us. 



& 



Triploid. nature of endosperm. — Since the discovery of the 

 phenomenon called " double fertilization " in angiospermic 

 plants by Nawaschin'^ and Guignard^^ in 1899, it is now a well 

 established fact that the endosperm-tissue of maize and of 

 most other angiospermic seeds is formed hy the further divisions 

 of the primary endosperm cell, whose nucleus is the product of 

 union of the two polar nuclei of the embryo-sac and one of 

 the two male nuclei from the pollen tube. Thus the endosperm 

 nucleus is the result of the union of three distinct nuclei, the 

 two of them belonging to one and the same female gametophyte 

 and the one derived from the male gametoph^'te. The endo- 

 sperm is thus, unlike the normal embrj'O of diploid nature, a 

 special kind of embryo of triploid nature, pursuing a transitory 



1) FocKE, W.O. Die Piianzenmischlingen. 1881 p. 517. 



2) Bull. Acad. Iinj). Sci. St.-Pdtersb. 9. pp. 377-382, 1899. 



3) Compt. Eend. 128. pp. 804-781. 1899. 



