20 CIRCULAE NO. 132_, BUEEAU OP PLANT INDUSTEY. 



"While these numerical relations adequately demonstrate the real- 

 ity of the phenomenon, it is not without interest to find cases in 

 which the tendency to coherence is manifested in another and more 

 direct way. 



Aleurone color, while in general alternative in its inheritance, often 

 appears in the form of a mosaic, the colored spots varying from 

 almost the entire surface of the seed to the contents of a single cell. 

 The texture of the endosperm is more uniform in, its behavior, mosaic 

 inheritance being very rare. In classifying upward of 100,000 seeds 

 only 8 have been observed in which the texture of the endosperm 

 was not uniform throughout the seed. In two of these seeds which 

 showed a mosaic endosperm the aleurone color also appeared in spots 

 and in both of these seeds the mottling of the two characters coincided. 



The fact that the spots of aleurone color and the segments of a 

 different endosperm texture corresponded was first noticed by Mr. 

 O. F. Cook in a seed from an ear (Dh359) that resulted from pol- 

 linating a plant of the Chinese variety having waxy endosperm and 

 colored aleurone with pollen from a white variety having the ordinary 

 horny endosperm. The aleurone color of the Chinese variety is al- 

 most completely recessive to the white of the Gracillima variety with 

 which it was here crossed, and the majority of the seeds were with- 

 out color. The remainder showed aleurone color in spots of varying 

 size. With the exception of the single seed in question all the seeds 

 of Dh359 were horny, waxy endosperm, being recessive to all other 

 forms of endosperm. In this one seed there was a small waxy area 

 directly beneath a spot of aleurone color and corresponding to it in 

 shape. 



The coincidence of the boundaries of the colored spot and waxy 

 area are so exact that the idea of the superposition being the result 

 of chance can not be entertained. 



The second example of mosaic coherence occurred in the second 

 generation of Dh209, a cross between a white waxy strain of Chinese 

 and a colored sweet variety.^ In one of the seeds of this ear the 

 endosperm was waxy except a portion comprising about one-fourth 

 of the seed, which was horny. The waxy portion was overlaid by a 

 white or colorless aleurone, while the aleurone over the horny portion 

 of the endosperm was a deep purple. 



In both of these mosaic seeds it will be noted that the association 

 of characters is the same as in the parental strains. Thus, in the 

 first example the Chinese parent having the waxy endosperm had a 

 colored aleurone and in the mosaic seed the waxy portion is overlaid 



1 For a discussion of these hybrids, see Collins, G. N., and Kempton, J. H., Inheritance of waxy endo- 

 sperm in hybrids with sweet corn, U. S. Department of Agriculture, Bureau of Plant Industry, Circular 

 120, pp. 21-27, iyi3. 



[Cir. 132] 



