46 THEORY OF EVOLUTION 



The explanation of the failure to produce a 

 pure race of Andalusians is that they are like 

 the pink flowers of the four o'clock, i.e., they are 

 a hybrid type formed by the meeting of the 

 white and the black germ cells. If the whites 

 produced by the Andalusians are bred to the 



FIG. 16. Diagram showing history of germ cells of cross of 

 Fig. 15. The larger circles indicate the color of the birds; 

 their enclosed small circles the nature of the factors in the 

 germ cells of such birds. 



blacks (both being pure strains), all the off- 

 spring will be blue (fig. 15) ; if these blues are 

 inbred they will give 1 white, to 2 blues, to 1 



