SALPA IN RELATION 10 EVOLUTION OF LIFE. 137 



other, and many of them, like the blue-fish and the albacore, are 

 never satisfied with slaughter, but kill from mere sport. 



Insatiable rapacity must end in extermination unless there is 

 some unfailing supply, and as we find no visible supply in the 

 water of the ocean we must seek it with a microscope. By its aid 

 we find a wonderfully rich and diversified fauna made up of 

 innumerable larvoe of all sorts of marine animals, together with a 

 few minute and simple metazoa, but these things cannot form the 

 food-supply of the ocean. It is clear that a single carnivorous 

 animal could not exist very long by devouring its own children, 

 and the result must be the same however great the number of 

 individuals or species. 



The total amount of these organisms is inconsiderable, however, 

 when compared with the abundance of a few forms of protozoa 

 and protophytes, and both observation and deduction force us to 

 recognize that the most important element in the total amount of 

 marine life consists of some half-a-dozen types of protozoa and 

 unicellular plants, of globigerinse and radiolarians, and of tricho- 

 desmium, pyrocystis, protococcus, and the coccospheres, rhabdo- 

 spheres and diatomes. 



Modern microscopic research has shown that these simple 

 plants, and the globigerinse and radiolarians which feed upon 

 them, are so abundant and prolific that they meet all the 

 demands made upon them and supply the food for all the 

 animals of the ocean. 



This is the fundamental conception of marine biology. The 

 basis of all the life in the modern ocean is to be sought in the 

 micro-organisms of the surface. 



This is not all. The simplicity and abundance of the micro- 

 scopic forms and their importance in the economy of nature show 

 that the organic world has gradually shaped itself around and has 

 been controlled by them. 



They are not only the fundamental food-supply, but the primeval 

 supply, which has determined the whole course of the evolution of 

 marine life. 



The pelagic plant-life of the ocean has retained its primitive 

 simplicity on account of the very favorable character of its environ- 



