202 MANTON COPELAND 
snails. When resting, sea water squirted over the siphon tip 
induced no locomotor response, whereas oyster juice stimulated 
the animal to activity and induced the proboscis reaction. It 
was noted, however, that the snail sometimes had difficulty in 
securing a piece of oyster which was placed in front of it. Its 
behavior emphasized what had already been observed, viz: 
that the tentacles aid the foot in the sensing and manipulation 
of food before it is taken into the mouth. 
It has been shown that the foot of Busycon is sensitive to 
food juices. Accordingly, tests were made to determine whether 
the direction of locomotion could be controlled by applying the 
oyster extract to this organ. A snail, which was resting in a 
corner of the aquarium, could not be stimulated to locomotion 
by squirting the extract on the foot margin or on one of the 
tentacles. Siphon stimulation, however, caused the animal to 
crawl up the end of the aquarium and to extend its proboscis. 
It was then led over to the side where it moved diagonally up- 
ward after stimulation. Oyster Juice was now applied to the 
right antero-lateral margin of the foot, but without directive 
effect, for the snail continued in its original course. Another 
animal was moving in a similar direction up the side of the 
aquarium. This time, the juice was applied to the left anterior 
margin of the foot, but the animal turned to the right and down- 
ward, or in a direction away from the location of the stimulating 
substance. By squirting the juice in front of the siphon whenever 
it was swung to the left, the animal was made to turn upward, 
and was soon crawling in the direction taken at first. Stimula- 
tion of the siphon system and not the foot, therefore, was effective 
in directing the snail toward the food juices. .In the course of 
these and other tests, it was found that the application of oyster 
extract to a limited portion of the anterior border of the foot of 
a moving snail often caused that part to slow down momentarily ; 
a reaction which may be compared to the local contraction of the 
stimulated foot margin of a resting snail already described and 
one which, if continued under the influence of a more concen- 
trated stimulus resulting from actual contact with food, would 
end in food procurement by the characteristic method of partly 
