42 THEORY OF EVOLUTION 



garden plant called four o'clock (Mirabilis jal- 

 apa) with red flowers is crossed to one having 

 white flowers, the offspring are pink (fig. 13). 

 The hybrid, then, is intermediate in the color of 





\7 PARENTS 



FIG. 13. Diagram illustrating a cross between a red (dark) 

 and a white variety of four o'clock (Mirabilis jalapa). 



its flowers between the two parents. If these 

 hybrids are inbred the offspring are white, pink 

 and red, in the proportion of 1:2:1. All of 

 these had the same ancestry, yet they are of 

 three different kinds. If we did not know their 



