The Law of Segregation 239 



others were crossed with the pure yellow-seeded parental 

 type, and with the pure green-seeded parental type. The 

 results of these experiments with hybrids showed that the 

 dominance of a trait in no sense destroyed its alternative, 

 but merely concealed it (Fig. 60). A hybrid plant bearing 

 yellow seeds is inherently different from a pure strain plant 

 bearing yellow seeds. This difference does not show out- 

 wardly but reveals itself in the following generation: we dis- 

 cover what is inherent by breeding. It is as true under ex- 

 perimental condition as it is in the world outside, " by their 

 fruits shall you know them." Self-fertilized hybrids pro- 

 duced offspring in which both of the alternative characteris- 

 tics were present — and always in a definite proportions 

 The offspring of hybrid parents showed three-fourths having 

 the dominant character, and one-fourth showing the alterna- 

 tive or recessive character (Fig. 60 and table on page 233). 



On crossing a hybrid yellow-seeded individual with a 

 pure green-seeded individual the offspring show both traits 

 in equal proportions. Here again the hybrid, although re- 

 sembling the dominant parent, shows that there is something 

 in the constitution that can reappear in subsequent genera- 

 tions, and this can be referred back to the ancestor that 

 manifested the recessive trait. On crossing yellow-seeded 

 hybrids with yellow-seeded plants of the pure parental stock, 

 the yield is 100 per cent of the yellow-seeded or dominant 

 type (see Fig. 61). These experiments show that the two 

 alternative traits found among the ancestors become sepa- 

 rated when hybrids are mated. This general fact of segre- 

 gation of inherited traits has been found to apply to hun- 

 dreds of characters in animals as well as in plants. No matter 

 how closely the hybrid individual resembles one of the 

 parents, a mating of hybrids will result in the reappearance 

 of the recessive trait in a certain proportion of cases. 



We should note here that this principle of segregation 

 applies even where dominance is incomplete. In the Anda- 

 lusian blues, for example, when two blues are mated the 

 offspring shows three types (white, black and blue) in deli- 



