VERTEBRATES: BACKBONE AND BRAIN 109 



ning to become one of wits, and the crown will soon 

 pass from the strongest to the shrewdest. Mind, not 

 muscle, much less digestion or reproduction, is the 

 goal of the animal kingdom. And we shall see later 

 that the mammalian mode of reproduction and of care 

 of the young led to an almost purely mental and moral 

 advance. For these could have but one logical out- 

 come, family life. And the family is the foundation of 

 society. And family and social life have been the 

 school in which man has been compelled to learn the 

 moral lessons, the application of which has made him 

 what he is. 



You must all, I think, have noticed that the different 

 systems of organs succeed one another in a certain 

 definite order ; and that each stage from the lowest to 

 the highest is characterized by the predominance of a 

 certain function or group of functions. This sequence 

 of functions is not a deduction but a fact. Place side 

 by side all possible genealogical trees of the animal 

 kingdom, whether founded on comparative anatomy, 

 embryology, palaeontology, or all combined. They 

 will all disclose this sequence of functions arranged in 

 the same order. Let me call your attention to the fact 

 that this order is not due to chance, but rests upon a 

 physiological basis. We might almost claim that if 

 the evolution of man from the single cell be granted, 

 no other order of their occurrence is possible. 



The protozoa are mostly, though not purely, nutri- 

 tive and reproductive. These functions are essential to 

 the existence of the species. Naturally in the early 

 protozoan colonies, and in forms like hydra, these func- 

 tions predominated. But mere digestive tissue is not 

 enough for digestion. Muscles are needed to draw the 



