232 THE PERPETUATION OF ADAPTATIONS 



degree, this is shown by the very fact of the enormous differ- 

 ences in organization of modern animals, some of which do not 

 vary in any marked degree from forms deposited some fifty 

 million years ago and found today as fossils. If the dictum 

 omne vivum ex vivo is true then all protoplasm must be of 

 approximately the same age, whether found in an amoeba or in 

 man. If protoplasm of all animals is equally old it follows that 

 some forms of it were endowed with a greater possibility of 

 variations and adaptations than others, or with a greater 

 " potential of evolution" so that certain types developed into 

 marvellously complicated organisms in the same period re- 

 quired by other types to develop into lower forms. Thus if 

 man and the coelenterates are equally old, the protoplasm which 

 was to develop into man must have been endowed with a 

 much greater potential of evolution than that which developed 

 into the coelenterates provided they had a similar environment. 



It is conceivable also, that in the period when protoplasm was 

 formed from non-living matter, the conditions were not always 

 the same and that the "best " protoplasm in the sense of possess- 

 ing the highest potential of evolution, was formed during a 

 limited part of the protoplasm -forming period, while protoplasm 

 less highly endowed was formed at other times when conditions 

 were less propitious. Bacteria and the lowest forms of both 

 plants and animals might be conceived as having come from 

 protoplasm formed during an unpropitious period and so poorly 

 endowed with the potential of evolution that some of them 

 never reach the stage of a perfect cell; others like the present 

 day infusoria and higher protozoa generally never progressed 

 beyond the single-celled stage. 



If from the coelenterates up, a monophyletic hypothesis is 

 adequate to explain present-day phyla, then we must admit that 

 with different types and under the conditions of their develop- 

 ment countless variations and evolution were impossible and 

 that certain types of structure would permit of many more 

 variations than do other types. Some modifications were cap- 

 able of great development; these were " lucky strikes" so to 

 speak, in evolution which enabled the organisms to respond 



