Inheritance in the Higher Plants 97 



cases may be more complex in appearance but this is a sur- 

 face complexity only. They yield to similar analyses when 

 they are properly understood. This complexity in appear- 

 ance has many times made cases appear to be exceptions 

 to Mendel's general law. Various ratios have been obtained 

 that were seemingly inexplicable, but these one by one have 

 been found to be merely variations of the simple ratios that 

 we have just discussed. Perhaps the most interesting of 

 these aberrant ratios are those cases of heredity dealing 

 with latent characters. We will consider some of these 

 briefly as examples of the various manifestations which are 

 found in the hereditary transmission of plant characters. 



One of the most important classes of latency we have just 

 discussed. It is called latency of separation. Where a 

 character exists through the interaction of two factors, 

 these factors may at some time become separated, that is, 

 possessed by different individuals. When this occurs the 

 character is apparently lost and does not again appear 

 unless two individuals bearing the complementary factors 

 are crossed. This is the explanation of the old phenome- 

 non of reversion after crossing. It was first explained by 

 Bateson from experiments with sweet peas. He found that 

 two white varieties yielded the purple color of the wild 

 sweet pea when crossed. In the same way I have found 

 that the white seeds in the dihybrid ratio of 9 : 7, shown 

 by the purple X non-purple cross of maize varieties, gi\-e 

 purple seeds when crossed at random. The non-purples 

 exist in the following ratios: 



