GENETIC VARIATIONS 353 



or seeds, and it can be shown that these different colors are 

 due to different mutations of certain genes, in the cells that 

 produce the differently colored parts. This is proved by the 

 fact that when germ cells are produced by the differently 

 colored parts of the plant, the color of the parts from which 

 they come is inherited in the offspring produced from the 

 germ cells. This shows that the genes have been altered in 

 the different parts. The inheritance of color in such cases 

 occurs in the usual Mendelian way, but is usually not com- 

 plete. That is, in the plants of the next generation there 

 again occur gene mutations, giving rise again to different 

 colors in the different parts of the plant. 



Thus in maize, ^^ the seed coverings or pericarp on the 

 grains frequently vary in color, so that on a single ear some 

 of the grains are red, some are white, some are variegated 

 red and white, in various degrees. These diversely-colored 

 seed coverings are part of the parent plant. When from self- 

 fertilized plants, seeds with red pericarp are planted, they 

 produce plants with prevailingly red seeds; seeds with white 

 pericarp yield plants with prevailingly white seeds; seeds 

 with variegated pericarp produce plants that have again 

 variegated seeds. This shows that the genes in the germ 

 cells (seeds) are mutated in the same way as those in the 

 neighboring body cells (pericarp) of the parent. What has 

 happened is that in early development the genes in certain 

 cells have become mutated in various different ways. From 

 a single such cell are produced later both body cells (peri- 

 carp) and germ cells, with the genes so changed as to give a 

 certain color. 



Thus in such cases mutation of some of the genes might 

 be considered a normal feature of the development of the 

 individual. In many animals different parts of the body cov- 

 ering (hair, etc.,) are of different colors, as in spotted rab- 

 bits, guinea pigs and the like. It appears possible that the 

 different colors are due to different mutations of the genes 



