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4,—THE FOOD OF THE OYSTER, CLAM, AND RIBBED MUSSEL, 
By JoHN P. Lotsy, PH. D. 
During a stay on the James River, Virginia, in the summer of 1892, 
I had hoped to study the food supply of both the young (embryonic) 
and the adult oyster, but as the season was too far advanced to allow 
the collection of any embryos only the latter part of the investigation 
proved feasible. 
Collections were made at many places on both sides of the James 
River from Newport News to Old Point Comfort, specimens being 
obtained from both natural and cultivated beds, from muddy and 
sandy bottom, and from piles and stones, especially around Fort Wool 
on the Ripraps. They were taken from various depths, some being 
gathered on a bottom left exposed at low tide; others were obtained 
which did not grow on the bottom, but which were, so to speak, sus- 
_ pended in the water near the surface, attached to piles and rocks, also 
exposed during low tide; still others were collected from deeper places, 
never uncovered by the tide, growing either on the bottom or on per- 
manently submerged stones and piles. To determine whether any 
changes in the food supply were dependent upon the season of the year, 
material was obtained daily from the beginning of June until the end 
of September, and whenever an opportunity offered shipments brought 
from farther up the river were examined to see if the greater amount 
of fresh water there present had any influence on the character of 
their food. 
Before entering further into details it is necessary to note that the 
oyster is constantly ingesting a stream of water, which, passing the 
mouth, brings near and into this always opened organ all the objects of 
greater or less size coming within the influence of this stream. The 
mere presence, therefore, of particles of various organic matter in its 
stomach, even in great quantities, does not indicate that the oyster 
uses them as food, but only proves that these particles were present in 
the surrounding water at the time of ingestion. This is a consider- 
ation too often overlooked. If an animal of the structure of an oyster 
be placed in a bucket of water in which is suspended a great number 
of carmine granules, these granules will doubtless be found in the 
stomach of the animal after a certain length of time, yet nobody would 
claim that they were the food of the oyster. A similar thing occurs in 
nature. In the many oysters which I have opened and of which I 
investigated the stomach contents I never failed to find numerous 
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