286 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 



storms, by cold rains, and by sndden falls in temperature, and the 

 prevalence of such weather during the spawning season must have an 

 important effect upon the set of sjiat. 



FOOD, 



The oyster feeds upon both animal and vegetable food, the particles of 

 which are of microscopic dimensions. The fry and young spat consume 

 relatively large quantities of bacteria and monads, among the most 

 minute organisms known to microscopists. According to Dr. Eyder: 



Many of the food balls found in the intestine of the recently attached spat will 

 measure under rnorrTT inch lu diameter. The cavity of the little creature's stomach 

 measures only ^TnnT inch. Yet in this minute digestive cavity the food is actually 

 found rotating in the form of minute rounded and oval bodies, which are kept in 

 motion by the action of the cilia which line the stomach. That these bodies must 

 have been of about the size noted when they were originally swallowed and as seen 

 rotating in the stomach is evident from the fact that the young oysters, like the 

 adults, are wholly without teeth or triturating organs of any fiind. 



This minute kind of vegetable and animal food is found more or less abundantly 

 in all sea water, and is especially abundant during the spawning season, when the 

 decomposition and disintegration of all kinds of minute organic debris floating about 

 in the water is in rajiid progress, owing to the prevalent high temperature of the 

 air and water. It is, therefore, probable that very few otherwise suitnble locations 

 exist where it is not possible to find an abundance of the proper sort of food for the 

 oyster during its very earliest stages of growth. 



The food of the slightly more advanced spat and the adults is found to consist of 

 diatoms, rhizopods, infusoria of all kinds, monads, spores of alga', pollen grains 

 blown from trees and plants on shore, their own larvaj or fry, as well as that of many 

 other mollusks, of bryozoa and minute embryos of polyps and worms, together with 

 other fragments of animal or vegetable origin, and sometimes even minute crusta- 

 ceans. In variety of food the oyster, therefore, has a wide range of choice. There 

 are also few locations otherwise well adapted which will not supply an abundance 

 of food for the animal, which, it is to be remembered, captures and hoards millions 

 of these minute plants and creatures in its stomach, where they are digested and 

 incorporated into its own organization. It therefore follows that when we eat an 

 oyster we are consuming what it required luillions of the minutest organisms in the 

 world to nourish. The oyster is consequently a sort of living storehouse for the 

 incorjioration and appropriation of the minute life of the sea, which could never be 

 rendered tributary to the food supply of mankind in any other way except through 

 the action, growth, and organization of this mollusk.* 



The quantity of young oysters consumed by the adults is doubtless 

 enormous, 200 fry having been found in the stomach of single individ- 

 uals. Not only the free-swimming fry, but eggs and spermatozoa are fed 

 upon, and an insight Is here gained into the ultimate fate of some of the 

 vast numbers of genital elements which the parents shed into the water. 



While the oyster feeds upon both plant and animal organisuis, it 

 must be remembered that it is primarily dependent upon the former. 

 That not only is the major portion ot the food of the oyster itself of 

 vegetable origin, but the minute animal forms are dependent for their 

 sustenance upon the plants and are not to be found in abundance far 

 removed from them. 



* Rept. U. S. F. C. 1885, pp. .387-388. 



