REPORT OF COMMISSIONERS OF INLAND FISHERIES. 23 
numbers perish without being fertilized. Of the numerous num- 
ber which reach the swimming stage of development, it is certain 
that only relatively few are successful in burrowing. During these 
early stages, not only are they preyed upon by innumerable small 
predaceous animals, but the chances of perishing by falling upon 
unfavorable ground where they are smothered by the silt, or where 
they cannot burrow on account of the rocks, are equal, if not 
greater than their chances of falling upon good ground. When 
they begin to burrow they are subject to the attacks of the crabs, 
eels, star-fish, and probably many other enemies; and those which 
attain a somewhat greater age are continually being dug out of 
their burrows by man, and thus exposed to the attacks of fishes and 
all other enemies, even if they are not actually carried away by the 
clam-diggers. There is some evidence that in certain parts of the 
Bay the red water has worked havoc among the clams, as was 
mentioned in the last report. It is probable, however, that the 
excessive and indiscriminate digging is largely responsible for the 
decrease in the clam product of the Bay. 
The clam gets its food-supply from the sea-water, which is 
drawn in through the incurrent openings of the snout or siphon. 
It consists of microscopic organisms of various sorts, a large por- 
tion being diatoms. The abundance of this food varies in differ- 
ent localities, and in the different depths of water, and at the vari- 
ous times of the year. The clam feeds continuously, if it is com- 
fortably situated, when covered with water. 
Summary oF Previous EXPERIMENTS. 
The observations of the natural history of the clam, which have 
been summarized briefly above, suggested numerous problems re- 
lating to clam propagation, which required experimental tests. 
Methods of Collecting Clam-Spat.—In oyster-culture, one great 
feature is a successful collection of spat; and the value of the 
oyster industry depends in not a small degree upon the economy 
and certainty with which such spat can be collected and trans- 
