198 
Proceedings of Royal Society of Edinburgh. [sess. 
On the Olfactory Organs of Helix. By Dr A. B. Griffiths, 
B.R.S. (Edin.), F.C.S., &c. 
(Read May 2, 1892.) 
Socliaczewer * has examined the olfactory organs in the Pulmo- 
fjasteropoda. In these animals the organ of Semper, the pedal 
gland, and the tentacnla have each been considered to have the 
function of an olfactory organ. Sochaczewer states that : {a) The 
organ of Semper is small in Helix^ Arion., and Limnceus ; but is 
well developed in Limax. In the last mentioned animal it has the 
form of four or five glandular lobate processes, which are set at the 
sides of the mouth. This organ is supplied with four nerve-fibres. 
The two median are muscular in character, while the lateral 
branches are the proper labial es, which give off, one on either side, a 
fine nerve-branch to the glandular branches of the organ of Semper. 
The cells of the constituent lobes resemble the glandular cells of the 
salivary glands ; in other words, this organ has not an olfactory 
function, if) The pedal gland is an olfactory organ. It is well 
supplied with nerves ; but experiments are difficult to try in such 
an organ, (c) The tentacula of Helix 'pomatia are not the seat of 
the olfactory organs. After having cut off the tentacula, and 
allowed the wounds to heal, he then placed the snails on a flat 
plate, the edge of which was smeared with turpentine. He says 
that both the mutilated and unmutilated specimens turned away 
from the edges, and he therefore concludes that this proves that the 
tentacula are not the seat of the olfactory organ. 
But Sochaczewer has overlooked the fact that the mutilated or ex- 
cised individuals receded from the turpentine because this fluid gave off 
an irritating vapour which acted on the sensitive tissues generally ; f 
Zeitschrift fur Wissenschaftliche Zoolgie, vol. 35, p. 30. 
t It should be borne in mind that the whole body is extremely sensitive to 
the action of irritating vapours ; and in the tentacula this sensitiveness is 
much more delicate than over the general surface. 
