454 
BULLETIN OF THE BUREAU OF FISHERIES. 
drawn in rapidly. At 9.50 a. m. the debris was cleared off the region over the 
palps, mouth, and esophagus, so that the light could penetrate. Debris was then 
piled over the inhalent siphon so that a great quantity was passing in and between 
the palps. Great streams of this passed downward, and a heavy rope of material 
poured off the posterior corner of the palp. A good many particles and masses of 
mucus-entangled material passed forward across the upper part of the inner faces 
of the palps to the mouth. These sometimes stopped along the way for a time as 
if the palps pressed together and held them. There was no doubt at all that some 
material was ingested. 
Some carmine was mixed with sand and debris, and at 10.15 a. m. the mussel 
was arranged as before, so that the palps, etc., could be seen. Then the mixture 
was left piled over the siphon as before. The valves opened and closed a few times 
and then admitted some material — carmine, sand grains, and debris — some of 
which was seen to pass between the palps to the esophagus and mouth. A heavy 
stream passed off the palps, of course, at the same time. Soon, however, the 
valves closed and the mussel did not reopen them. On being removed to clear 
water red material could be seen in the stomach and the loop of the intestine. 
This mussel ingested material, although the water was so heavily laden the siphons 
were completely buried and a heavy strand was passing off the posterior lower 
corner of the palp all the time. This strand or mucous rope of material was at 
least 40 micra wide most of the time. 
In the clear water with no carmine, as the foot was stretched out, cilia having 
begun moving in the stomach, it could be seen that the material in the interior part 
of the intestine, at least as far down as the loop, was rotating. This was no doubt 
due to the rotation of the crystalline style. 
At 11.15 a. m. red particles began to be observed in the feces; also multitudes 
of sand grains. In one small mass were 3 sand grains, about 30 by 30 micra, and 
one 60 by 30, besides more minute ones. In another was a grain 40 by 30 by 25 
micra. 
Two specimens of Lampsilis luteola, one 4 mm. long and one 2-|, were kept in 
clear water a few hours until the alimentary canal was quite empty throughout. 
They were then placed in such a heavy suspension of debris from the rearing trough 
that the mussels could not be seen. The suspension was agitated with a fine glass 
rod, so that the mussles were kept covered during the experiment, which continued 
from 4.30 to 5.15 p. m. At the end of that time so much material had been ingested 
that the rectum appeared as a solid black line as far as the anus. 
MUSSELS 4 MM. LONG. 
The outer gill has not yet developed. A specimen of Lampsilis luteola was placed 
in a suspension of carmine at 9.45 a. m. Carmine began to pass in and accumulate 
in oval boluses in the esophagus. Each bolus passed into the stomach in a swift 
gulp, so to speak, several seconds to a half minute between gulps. After about 10 
minutes the stomach appeared red from the carmine being rotated there by the cilia. 
Then the loop of the intestine began to appear red. About this time the mussel 
ceased ingesting and was removed to clear water. The remainder of the carmine 
