OLFACTORY REACTIONS OF MARINE SNAILS 193 
oysters and oyster juice were used in feeding and stimulating 
the snails. The extract was prepared by first removing the soft 
parts of the oyster from the shell, and placing them in a small 
amount of sea water. This was usually done the day before the 
material was used. The oyster was then ground in the sea water 
with a pestle and the extract filtered out. 
The foot, mantle and tentacles. All of the external soft parts 
of the body of Busycon which were tested were found to be 
sensitive to food juices. The snails frequently crawled up the 
sides of the aquarium and rested at the surface partly out of the 
water. In that position the anterior margin, and sometimes a 
portion of the under surface of the foot could be readily tested. 
Dropping sea water on these exposed parts of the foot produced 
little or no effect, whereas a single drop of oyster extract called 
forth a well marked local contraction of the stimulated area 
By removing the snails from the water, other portions of the 
body surface were rendered more accessible. The animals were 
placed on their backs and sea water dropped from a pipette 
around the mantle edge and on the proximal external surface, 
and the partly opened distal end of the siphon. There was 
no reaction noted except at the siphon tip, where there some- 
times occurred a very slight contraction. Drops of oyster juice, 
however, caused contraction of the mantle edge and the surface 
of the siphon. When the end of the siphon was stimulated, it 
was drawn back farther into the shell. The last was the most 
marked reaction. 
As in Alectrion, the tentacles of the whelk were found to be 
very sensitive to food extracts. When stimulated under water 
with fish or oyster Juice, the tips contracted and usually were 
bent somewhat to one side. When fish extracts mixed with 
carmine was squirted over a tentacle, or the anterior margin of 
the foot of a snail resting in the water, the proboscis was usually 
extended, after a time, near the stimulated region. The same 
reaction occurred after the tentacles had been removed when the 
juice was applied to the anterior part of the foot and the regions 
beneath the base of the siphon. <A notch in the foot margin 
was formed by the local contraction and lifting of the stimu- 
THE JOURNAL OF EXPERIMENTAL ZOOLOGY, VOL. 25, No. 1 
