Growth Integration 



99 





Illustrations from Plants 



But it is in the plant world that these graded series of 

 homonjmous parts in individual organisms are most strik- 

 ingly seen. It occurs in what is perhaps its most typical, 

 least modified expression in the arrangement and size rela- 

 tion of parts in the leaves of many ferns and palms. But 

 the compound leaves of innumerable flowering plants illus- 

 trate it very beautifully. Figures 58, 59, and 60 (Acacia, 

 Vicia and Cassia) show three types of compound leaves 

 based on the mode of gradation of the leaflets. These might 



FIGURE 58. ACACIA ELATA. 



