RELATIONS TO OTHER SCIENCES 693 



less abundant now than in the primeval ocean. Lime has also been 

 extracted in greater abundance in recent than in ancient seas. This 

 occurs especially in the warmest and saltest seas. 



Marine organisms have had to accommodate themselves to the 

 slowly-changing conditions of the ocean which I have just indicated, 

 and it seems evident that the animal and vegetable protoplasm must 

 have established fixed relations with the elements in solution in sea- 

 water. This relation would almost certainly be handed on by heredity, 

 for there is no reason for supposing that morphological structure can 

 be handed down in this way, and not chemical composition. When 

 we have a fuller knowledge of the chemical composition of the soft 

 tissues of the different groups of marine organisms, and of the com- 

 position of their circulatory fluids, we may possibly be able to read 

 the history of the ocean as clearly as the paleontologist reads the 

 history of the rocks. 



