88 THE EVOLUTION OF LIVING BEINGS. 



black and grey children, on the other hand, would betray 

 its hybrid nature. 



In the same manner mating grey females with a 

 black male would reveal to us the purity or impurity 

 of the grey female which, if pure, would get grey chil- 

 dren only, if impure, grey and black ones. An impure 

 grey male and an impure grey female, so found out, 

 paired together, would give a certain percentage of black 

 children and thus prove our contention that there must 

 be hybrids among the apparently pure wild grey rabbits. 



The quickest way to obtain such impure greys would 

 probably be to catch a pregnant black female, as such 

 a one is very likely to owe its pregnancy to a grey male, 

 pure or impure, and consequently will either throw a 

 litter of exclusively impure greys or consisting of a 

 mixture of impure greys and pure blacks. 



The fact that in Java frequently black and spotted 

 panthers are found in the same litter, is conclusive 

 proof that among either the black or the spotted 

 panther in Java, there are hybrid individuals. 



All such kinds of impurity are much easier demonstra- 

 ted in the case of plants which can be selffertilized, be- 

 cause here isolation of a sufficiently large number of 

 individuals of the phenotypically dominant type re- 

 veals to us, by their several progenies, at once the pre- 

 sence of hybrids. 



In this way, I was able to show that among our or- 

 dinary brown wallflowers (Cheiranthus Cheiri) some 

 are pure dominants, while others are hybrids, segrega- 

 ting violets, golden-yellows and whites, thus showing 

 that the wallflower is not a species but a Linneon, con- 



