338 THE HISTORY OF CREATION. 



ment of geological periods. Our life is a single drop in 

 the ocean of eternity. The reader may call to mind the 

 duration of life of many trees which is more than fifty 

 times as long ; for example, the dragon-trees (Dracaena) and 

 monkey bread-fruit trees (Adansonia), whose individual life 

 exceeds a period of five thousand years ; and, on the other 

 hand, the shortness of the individual life of many of the 

 lower animals, for example, the infusoria, where the indi- 

 vidual, as such, lives but a few days, or even but a few 

 hours, contrasts no less strongly with human longevity. 

 This comparison brings the relative nature of all measure- 

 ment of time very clearly before us. If the theory of de- 

 velopment be true at all, there must certainly have elapsed 

 immense periods, utterly inconceivable to us, during which 

 the gradual historical development of the animal and vege- 

 table kingdom proceeded by the slow transformation of 

 species. There is, however, not a single reason for accept- 

 ing a definite limit for the length of these periods of 

 development. 



A second main objection which many, and more especially 

 systematic zoologists and botanists, raise against the theory 

 of descent, is that no transition forms between the 

 difierent species can be found, although according to the 

 theory of descent they ought to be found in great numbers. 

 This objection is partly well founded and partly not so, for 

 there does exist an extraordinarily large number of tran- 

 sition forms between living, as well as between extinct 

 species, especially where we have an opportunity of seeing 

 and comparing very numerous individuals of kindred species. 

 Those careful investigators of individual species who so 

 frequently raise this objection are the very persons 



