Physiology of Helix Pomatia. 97 



M. Gaspard's experiments on this and other species prove that 

 although the approach of cold may be considered as the principal 

 cause of their hibernation, yet it is not the only one, as he failed 

 to produce this effect by submitting them to artificial cold, nearly 

 to the freezing point, and he found that they hibernate at the 

 proper period, at very different degrees of temperature, varying, 

 according to the table which he has given, from 2° to 20° R. (37' 

 to 77* Fahr.) 



Proceeding to an examination of the state of the vital functions 

 during the period of hibernation, the following are the results of 

 the author's numerous and minute experiments. It is of course 

 evident without requiring proof, that generation, sensation, the 

 cerebral and nervous functions, and locomotion, are totally sus- 

 pended. The only indication of irritability perceptible during 

 this period, is a slight contraction of the collar of the mantle when 

 touched, on removing the operculum. 



It is therefore to the functions of digestion, circulation, respi- 

 ration, animal heat, nutrition, secretions, and absorption, that 

 these experiments refer. 



§. 8. As these animals eat nothing during the period of hiber- 

 nation, digestion is of course suspended. Dissection of many in- 

 dividuals in this state, discovered the stomach entirely empty, and 

 the intestines filled with a brown thick liquid, but without the 

 least trace of excrement. 



§ 9. If in the month of November, before the severe cold sets 

 in, a portion of the shell of an operculated snail be removed, the 

 heart is seen contracting regularly, but feebly and with a very 

 slow pulsation. But if it be thus exposed during the winter, 

 when the temperature is down to the freezing point, it is found to 

 have totally ceased to beat. On exposure to a slight degree of 

 warmth the motions of the heart are renewed, and again suspend- 

 ed on its removal. This may be often repeated with the same re- 

 found in greater quantities in chalky districts. That lime is not necessary to 

 be eaten, in order to the perfect formation of the operculum, is however proved 

 by many in my possession having formed that substance, though during the 

 whole summer they had no access to any preparation of lime. Still I have no 

 doubt that it may greatly assist in rendering it solid and efficient. B. . 



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