224 THE FOUNDATIONS OF ZOOLOGY 



that thousands would find ample room and food in a pint of water, 

 one can form some faint conception of their universal abundance. 



The organisms which are visible in the water of the ocean and 

 on the sea-bottom are almost universally engaged in devouring 

 each other, and many of them, like the bluefish, are never satis- 

 fied with slaughter, but kill for 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, which 

 shows us a wonderful fauna made up of innumerable larvae and 

 embryos and small animals, but these things cannot be the food 

 supply of the ocean, for no carnivorous animal could subsist very 

 long by devouring its own children. The total amount of these 

 animals is inconsiderable, however, when compared with the abun- 

 dance of a few forms of protozoa and protophytes, and both obser- 

 vation and deduction teach that the most important element in 

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

 unicellular plants ; of globigerina and radiolarians, and of trichodes- 

 mium, pyrocystis, protococcus and the coccospheres, rhabdospheres, 

 and diatoms. 



Modern microscopical research has shown that these simple 

 plants, and the globigerinas and radiolarians which feed upon them, 

 are so abundant and prolific that they meet all demands 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 found 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 taken shape around them as 

 its centre or starting-point, 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 envi- 

 ronment, and the higher rank of the littoral vegetation and that of 

 the land is the result of hardship. 



On land the mineral elements of plant food are slowly supplied, 



