Xo. 626] SHORTER ARTICLES AND DISCUSSIOX 



271 



stood, and full allowance being made for the recognized effects 

 of inbreeding, it is not believed that there is any clear evidence 

 that he produced a single neiv hereditary characteristic in maize. 



But not all of the assumptions of fundamentals upon which 

 geneticists have based their work on maize have been so unhap- 

 pily chosen as those cited. Most of the work that has been done 

 on the heredity of endosperm characters depends upon the so- 

 called "double fecundation" and upon the degeneracy of three 

 of the four potential megaspores. The former of these facts was 

 observed by Guignard^ in 1901, but he did not figure it; the 

 latter has been deduced by analogy. Circumstantial evidence 

 was good in both eases, but evidence of this kind is not always 

 dependable. No one would risk much in a financial way on 

 chances like these, but some geneticists have risked years of 

 work. In a recent paper^ the writer has verified the facts as- 

 sumed in this work. 



The peculiar behavior of reciprocal crosses between varieties 

 of corn ditfering in the physical nature of the starchy endosperm, 

 has been explained' by the assumption that the two hereditary 

 factors presumably carried by the two polar nuclei be dominant 

 to the one factor carried by the sperm entering into the consti- 

 tution of the primary endosperm nucleus. This idea is in accord 

 with the multiple factor hypothesis, and the phenomenon is one 

 of the few direct evidences that we have as to the behavior of a 

 double application of a factor as opposed to a single application 

 of its allelomorph. But so little is known of the morphology 

 and the chemistry of these two kinds of starch and their relation 

 to the surrounding tissues that it is not at all iiuproltable that 

 the explanation advanced may be modified by the lesults of 

 further investigation. 



An interesting light is thrown upon the the multiple factor 

 theory by certain other morphological peculiarities of the grain 

 of corn. The essential idea of the multiple factor hypothesis, in 

 a simple form, is tliat a single visible effect may be due to two 

 or more factors, only one of wliicli is necessary to produce the 

 same effect, at least in a limited (h-ire. Little is known of the 

 relative natnres of tlie two or iiioiv factors that compose the mul- 

 tiple unit in tlie eases that have heen in vst i-'ated ; they may be 

 s Guignar.l, L., "La -lou!,!,. tV.,.,„;.;;ition .i.ui^ Ma.^."' Jour, de Bot., 



in the Endosperm of Zen Minis/ - Bull. Tormj Cliih. Iti : 7:i--90, 1919. 



^ Hayes, H. K., an.l ?:ast. K. ^t.. " I<\irthor Experitnciits on Inheritance 

 in Maize," Bull. Conn. Agr. Expt. Sta., 188, pp. 12-13, 1915. 



