190 MANTON COPELAND 
meter in length, and open at the end as well as below. Five 
stimulations of the foot processes failed to produce the proboscis 
reaction. The processes contracted as before, but the stimulus 
was not adequately tested with the stub of the siphon. When, 
however, a piece of fish muscle was placed in front of the snail, 
and when the juice was applied beneath the siphon, the proboscis 
reaction occurred. Repeated stimulations of the foot processes 
resulted in'a limited number of proboscis thrusts, and on the 
following day, the animal’s responses were again studied very 
carefully. In twelve trials there was only one typical proboscis 
reaction following the stimulation and contraction of the foot 
processes, and in this case the juice was squirted too far forward 
beneath the siphon. In three trials the proboscis was momen- 
tarily extended as the snail moved away from the extract, as if 
it had been only weakly stimulated, and in one trial the animal 
turned slightly toward the stimulating material when the pro- 
boscis was thrust once. In the remaining trials, although the 
foot processes contracted, the extract was not tested by the 
siphon stub, and the proboscis did not appear. When, however, 
after these tests and on the following day, the extract was 
dropped in front of or into what was left of the siphon, the pro- 
boseis reaction followed. Ten tests were made. This snail 
was again experimented upon in the condition described above, 
and also with a thread tied around the end of the cut siphon, 
which of course restricted its action still more. It should be 
understood that, on account of the slit in the ventral wall of the 
organ, it was impossible to render the extreme proximal part 
completely functionless. Whenever the stimulation of the foot 
process caused the animal to stop and test the environment with 
the base of its siphon, the characteristic proboscis protusion 
took place. Every trial with fish extract was preceded by one 
with sea water and carmine, but the latter never called forth the 
proboscis reaction. 
Several other individuals, with the siphons for the greater 
part of their length tied or cut off, and with and without tentacles, 
were carefully tested in a similar way, but as the results obtained 
were in accordance with those described, it is unnecessary to 
