Dr Davy's Observations on the Centipede. 387 



of which I shall give. It may be premised that the two 

 snails, on which the observations were made, were brought 

 from Tobago to Barbadoes ; had been several days fasting 

 (leaves were given them, which they did not eat), and that 

 they were kept under a glass vessel to which air had freely 

 access, in a well-ventilated room ; and farther, that, at the 

 same time, their temperature was ascertained by introdu- 

 cing a delicate thermometer with a projecting bulb, so as to 

 be covered with their soft parts, the temperature of the air 

 of the room was likewise ascertained ; and also, except on 

 the first day, that of a bottle of water standing by, for com- 

 parison : — 



These results seem to shew that these snails had a tem- 

 perature, commonly exceeding a little that of the atmosphere 

 in which they were. 



The two snails were found equal in volume to 10 cubic 

 inches. On the second of August, they were put wnder a jar 

 of the capacity of 240 cubic inches, full of atmospheric air, 

 and water was poured on the stand so as to cut off all com- 

 munication with the atmosphere. In this moist air, moist in- 

 deed to perfect saturation, the snails the first day were very 

 active, in constant motion ; on the second day they were less 

 so ; on the third day they were found dead. The air now on 

 examination was found to be largely vitiated with carbonic 

 acid gas. 32 cubic inches of this gas were absorbed by cream 

 of lime, leaving 198 cubic inches, 10 cubic inches having been 

 displaced by the volume of the snails. Hence it appears, 

 that nearly two-thirds of the oxygen had been consumed, con- 

 verted into carbonic acid gas, which may tolerably account 

 for the temperature of the snails being, as denoted in the 

 observations recorded, a little higher than that of the air. 



Tlie comparatively short time that the snails lived in a 



