CHAPTER XL 



BACTERIA IN THE SEA. 



So far I have alluded only very casually to the bacteria of the 

 sea. Because of their universal distribution and their special 

 modes of nutrition these micro-organisms do not fit into any 

 general scheme of classification such as we have considered with 

 regard to the other organisms in the sea. They belong to the 

 benthos, for we find them in the muds and oozes at the sea bottom; 

 but they belong also to the plankton, for we find them everywhere 

 diffused throughout the water of the sea. Both in the sea and on 

 the land the bacteria are quite ubiquitous, and there is hardly any 

 object in animate and inanimate nature which does not harbour 

 them. They abound on the surfaces of both terrestrial plants and 

 animals, and they are found in the cavities of the latter which are 

 in communication with the outside world ; while in some diseased 

 states almost every organ and tissue of the animal body may 

 contain them. It is because of their universal occurrence in 

 nature, and also because of their peculiar reactions toward dead 

 organic substance and toward the inorganic food materials of 

 organisms, that the bacteria are of such extraordinary importance 

 in the " household of nature." 



Note that quite special methods of investigation have to be 

 adopted in studying them. No net that can be devised is fine 

 enough to catch marine bacteria. We can indeed separate them 

 from water by means of porcelain filters, but this is hardly a 

 means of collecting them. They are always obtained from sea 

 water, or from mud, or from the surfaces or parts of the bodies of 

 organisms, by taking a small portion of any of these materials and 



