210 MANTON COPELAND 
ance, and exhibiting behavior characteristic of healthy animals. 
It soon became evident that some of the snails operated upon 
responded in the usual way to oyster extract. They followed 
it about the aquarium, extended their proboscides and ate 
pieces of oysters. Records of the behavior of ten individuals 
indicated clearly that they were still scenting food. About as 
many others treated by the same methods showed a complete, 
or nearly complete suppression of normal olfactory response. 
A suspicion that the attempts at destroying the osphradia 
had not been entirely successful was confirmed when all but one 
or two of the entire series of animals were removed from their 
shells and examined. In every instance a considerable extent 
of the osphradium was still intact, usually about one-half of it, 
and always the deeper portion which was not visible at the 
time of the operation. In nearly all those cases where the organ 
had been scraped, the mantle showed a_hole, usually where the 
tissue of the osphradium had been destroyed. As before men- 
tioned, the mantle is very thin in the region of the osphradium, 
and in some instances the injured portion may have been rup- 
tured in removing the animal from its shell. In three individuals 
whose osphradia had been burned but not scraped, the organs 
upon examination appeared superficially normal in two cases, 
and somewhat singed in the third. All three responded char- 
acteristically to oyster extract after treatment. One of them, 
however, failed to show olfactory reactions for over a week 
after cauterization, although it always ate oysters and otherwise 
exhibited normal behavior. Response to oyster juice was clearly 
indicated later. 
The fact that the mantle was apparently uninjured when the 
osphradium was burned was a feature of the results which led 
to a continuation of the cauterization method. It was evident 
that the organ should be more severely burned by an instrument 
which would retain the heat longer than a platinum wire heated 
over a gas flame. The desideratum was obtained in the form 
of an electrically heated cautery provided with a handle which 
permitted control of the current. After considerable experi- 
mentation it was found that the deeper portion of the osphradium 
