224 MANTON COPELAND 
the taste receptors of the tentacle or foot; this probably called 
forth contractions and the sudden movement of the siphon. 
' By the time the extract was taken into the siphon, it was diluted 
with sea water, but was still strong enough to bring about 
stimulation of the olfactory organ, which in turn initiated the 
proboscis reaction. When the greater part of the siphon was 
cut off, so that the persisting stub failed to reach the diluted 
extract, the gustatory stimulation alone was in most instances 
too weak or transitory to bring about more than local contractions, 
and accordingly the snail continued on its way without protrud- 
ing its proboscis. ‘Thus when the serial reactions are analyzed, 
they are seen to be partly gustatory and partly olfactory. 
To how great a degree the snails depend upon the olfactory 
sense in obtaining food has been impressively demonstrated. 
When very close to it, or even when in contact with it, a hungry 
animal deprived of the use of its olfactory organ may fail to 
sense it. No evidence was obtained to indicate that the eyes 
play any part in food procurement, but the tactile sense may be a 
factor in it under some circumstances. 
In a general way, it may be said that stimulations by relatively 
weak food solutions call forth locomotion or increase its rate, 
whereas stimulations by relatively strong ones bring about 
contractions and cessation of locomotion. Through stimulating 
the olfactory organ, the former direct the snail to food in the 
distance, and the latter, by stimulating the gustatory receptors 
as well, aid in the obtainment of it when at hand; and so, through 
stimulations by both, the snail procures its food without de- 
pending, to any great extent at least, on encountering other 
forms of stimuli. 
IV. SUMMARY 
1. Alectrion obsoleta and Busycon canaliculatum respond 
to stimulations by dilute food extracts and materials emanating 
from distant food, which enter their siphons, by increasing the 
rate of locomotion, or if resting, by moving forward and fre- 
quently by extruding their proboscides. 
