194 MANTON COPELAND 
lated area, and the proboscis was thrust downward through the 
opening. 
In these tests it was impossible to determine definitely whether 
the extract entered the base of the siphon before the proboscis 
was extended, but since the reaction was characteristically slow 
and a diffusion of the stimulating material took place, it seemed 
likely that it did. Moreover, when a snail was on the glass 
side of an aquarium, where the ventral surface of the siphon 
could be observed, it was noted that the lips of the organ spread 
apart near its base when it entered oyster extract which was 
being applied to the tentacles or foot; in fact, the split condition 
of the siphon appears to be partly an adaptation for taking in 
materials which are close to the body The part played by the 
chemical receptors of the tentacles and foot in responses to food 
stimuli will be fully considered in the succeeding account of the 
snails’ behavior. 
The siphon system. The most striking reaction of all was 
obtained by squirting the oyster extract in front of the end of 
the siphon so that it was taken into the organ in considerable 
amount. In the case of a moving snail, stimulation in this 
manner almost always caused it to increase its rate of locomotion, 
and to swing the siphon farther to the right and left. The 
lateral swinging of the siphon is characteristic of the moving 
animal and will be described in more detail later. Continued 
stimulations were usually sooner or later followed by an extension 
of the proboscis. 
When the extract was applied in the same way to a resting 
animal, in most instances it caused locomotion and the proboscis 
reaction. Even when the snail was much contracted the same 
response was noted. In all ‘cases the animal was first tested 
with sea water squirted from a pipette, which invariably failed 
to produce the reactions described above. Stimulation of a 
resting snail as large as Busyeon by the pipette method was 
particularly satisfactory, as the stream of oyster Juice could usu- 
ally be directed over the end of the siphon without coming in 
contact with the tentacles or other parts. 
