9.— BIOLOGICAL RESEARCH IN RELATION TO THE FISHERIES. 



BY JOHN A. RYDER, 



Professor of Comparative Embryology, University of Pennsylvania. 



There is no longer any questioning the fact that when we consider the economic 

 relations of one organism, the economic relations of multitudes of others are at 

 once involved. It may be that those others, thus brought under consideration, may, 

 as single individuals, be of no appreciable economic value to man; only when very 

 minute beings are gathered together in great numbers by other and useful organisms 

 as their staple of nourishment does their value become palpable. For example, a very 

 large and widely distributed group of plants found in fresh and salt water, the 

 diatoms, are very minute as individuals. Some of these diatoms have long been 

 used as test-objects in the trial of the power of resolution of the object-glasses of 

 microscopes. By many amateurs in science this is supposed to be their sole use. 

 The botanist, however, finds in them a wonderful exhibition of the power of a very 

 minute simple organic type to manifest the most manifold variations of the form and 

 superficial sculpturing of its siliceous envelope. To the economist and fish-cult urist 

 the diatoms have a totally different significance. Probably more than one-half of the 

 food of the oyster consists of these minute vegetable organisms. Therefore, one-half 

 of the sapid parts of the oysters us'd as the food of man represents an equal volume 

 of minute organisms transubstantiated into the fiesh of this bivalve. These almost 

 infinitesimal vegetable motes that swarm in the sea- water, wherever oysters thrive, 

 are integrated into oyster flesh by the milliards by means of the wonderful processes 

 of prehension and assimilation manifested by this mollusk. An indefinitely little and 

 apparently useless organism is thus aggregated and transformed so as to build up by 

 infinitesimal increments another palpably large organism that is useful and valuable 

 to man as food. The oyster, as oue part of the harvest of the seas, is in reality largely 

 a harvest of these apparently useless diatoms transformed into something useful. 



Oysters that are found in different places differ wonderfully in their rates of 

 growth, conditions of flesh, etc. Why should this be so? It is hardly to be doubted 

 that these differences in the growth and conditions of oysters at different places is 

 correlated with the character and abundance of their food supply. If this is true, the 

 kind and relative abundance of diatoms must be studied at these different places if 

 we expect to find out the causes of the differences in flavor and quality of oysters from 

 different beds. We are thus brought to realize the fact that the scientific and accurate 

 study of an apparently useless minute organic type has direct and useful bearings 

 upon the production oi an important element of food supply. The very existence of 

 oysters in a given locality is therefore dependent upon the abundant production of a 

 few types of microscopic organisms at that place. Whatever, therefore, impairs the 

 power of these minute organisms to reproduce themselves in such places must impair 

 the productiveness of the oyster beds in the same situations. It is also obvious that, 

 if we would most profitably study the welfare of the oyster beds on our coasts, we 



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