EVOLUTION 



935 



and the free-swimming, aggressive, luminescent Portuguese-Men- 

 of-War; between the fixed rock-barnacle, attached he ad- downwards, 

 wafting its food into its mouth with its curl-like appendages, and 

 the frolicsome shrimps and prawns; between limpets and sea- 

 butterflies, sea-slugs and octopuses; between the fixed ascidian and 

 the lightly-built pelagic salps ; between tortoise and Flying Dragon ; 

 between reptile and bird; between the ground-sloth and the bat 

 flying high. No doubt all sorts of secondary adaptations, e.g. to 

 different habitats and diets, have to be taken into account; but to 

 begin with there has been, we think, a fundamental divergence 

 between the relatively anabolic and the relatively katabolic. the 

 more conservative and the more adventurous, the saving and the 

 spending habit. 



It is of interest to look at a summary mapping out of the great 

 phyla and classes of animals to see that even the larger divisions 

 illustrate our thesis. 



Birds 



Mammals 



(Medusae) 

 (Medusoids) 



Coelentera 



(Corals) 

 (Zoophytes) 



(Infusorians) 



(Rhizopods) 

 Protozoa 



Sponges 



(Sporozoa) 



