A PECULIAR GRAIN OF CORN 



A chimera in a grain of corn caused by the occurrence of a factor mutation in a single cell at 

 an early stage of aleurone development. Colors purple and white. (Fig, la.) 

 A chimera involving a smaller area of changed aleurone tissue. Colors purple and yellow. 

 (Fig. lb, at right.) 



A more probable explanation of this 

 two-color phenomenon in corn is the 

 occurrence of a vegetative factor muta- 

 tion in meristematic tissue causing the 

 development of a chimera. The result 

 could be produced by the occurrence of 

 a mutation affecting the aleurone color 

 factor in one of the cells at a very early 

 stage of the development and growth of 

 the zygote, such that all cells descend- 

 ing from the mutated cell would have 

 the white aleurone layer. The applica- 

 tion of the mutation idea adequately 

 accounts for the occurrence of areas 

 or stripes of white, which are less than 

 one-half of the surface of the grain, as 

 in Fig. lb. Some of the F^ grains from 

 the one shown in Fig. la had only a 

 bmall spot of white aleurone, which was 

 surrounded by purple. These white 

 cells may be considered as the out- 

 growth of a single cell in which muta- 

 tion occurred in the color factor much 

 later in the development of the aleurone 

 layer than was the case where approxi- 

 mately one-half of the grain was white. 

 The appearance of these smaller areas 

 cannot be adequately accounted for by 

 the theory of the independent develop- 

 ment of the second pollen nucleus and 

 ^f the endosperm nucleus, even when 

 4 



the additional evidence from endosperm 

 texture is not considered. 



If objection is raised to the applica- 

 tion of the mutation hypothesis here 

 because of the appearance of a number 

 of similar mutated individuals in the 

 same or the . immediately succeeding 

 generation, attention only need be called 

 to similar cases in other plants where 

 this sort of phenomenon reoccurs nmny 

 times, and has been explained as due 

 to mutation in vegetative tissue. Per- 

 haps the best known case is that of 

 citrous fruits containing one or more 

 sections differing in color or texture 

 from the remainder of the fruit. Bab- 

 cock and Clausen attribute the appear- 

 ance of partly red and partly white 

 colored gladiolus flowers on a plant of 

 the white variety known as "The Bride" 

 (Frontispiece) to a factor mutation in 

 meristematic tissue. Their account of its 

 appearance is as follows: "In 1915 

 there appeared in a row of 'The Bride' 

 a single stalk bearing partly red and 

 partly white flowers. That this grew 

 from a corm which was an offshoot 

 from a typical white flowering corm is 

 certain. Furthermore, that the muta- 

 tion occurred very early in the develop- 

 ment of this corm and not some time 

 during the growth of the flower stalk 



