PLANT AND ANIMAL EVOLUTION 109 



which might be chosen to show how character velocity in 

 plants follows exactly the same laws as in animals, namely, 

 characters are accelerated or retarded in race evolution and in 

 individual development in adaptation to the environmental and 

 individual needs of the organism. 



We shall see this mysterious law of character velocity 

 beautifully illustrated among the vertebrates, where of two 

 characters, lying side by side, one exhibits inertia, the other 

 momentum. 



It is difficult to resist the speculation that character velocity 

 in individual development and in evolution is also a phenom- 

 enon of physicochemical interaction in some way connected 

 with and under the control of chemical messengers which are 

 circulating in the system. 



