112 M. Flourens on the Effects of 



new climate, and also new animal and vegetable productions* 

 Even in the same climate the changes of temperature which 

 return with the seasons, bring along with them similar changes 

 in plants and animals ; and in the same climate, in the same 

 season, the different regions of the atmosphere have each a 

 peculiar temperature, and each has also its own animals and 

 vegetables. 



It is on these great relations between the productions of 

 climates and the seasons, and between climates and seasons 

 and their temperature, that a celebrated traveller, M. de 

 Humboldt, has founded the Laws of the Geographic distribu- 

 tion of Plants and Animals ; and similar relations evince be- 

 yond a doubt the extensive influence which temperature exer- 

 cises over life and organization. 



But, as will be proved by the following experiments, it is 

 not only on organization and life, taken collectively, that cold 

 exerts an influence. It acts upon each organ and upon each 

 function. It produces in each of these organs or of these 

 functions a specific effect ; and it is for the purpose of deter- 

 mining some of these effects upon animals that the following 

 experiments were undertaken. 



One of the most remarkable eff*ects of cold, and that of which 

 I shall first treat, is Hybernation, 



The name Hybernation is given to that species of torpidity 

 or lethargy in which some of the mammalia of our climates, 

 like the marmot for example, pass the season of cold. 



If we conceive to ourselves animals that have become cold, 

 senseless, immoveable, rolled up into a ball, spending from 

 three to four months in succession without eating, drinking, 

 breathing, and with their circulation almost extinct, — if we 

 then consider that the animals subject to hybernation differ in 

 no respect, at least in nothing sufficient to account for the 

 singularity of the eff*ects produced, from other animals very near 

 to them and not subject to hybernation ; — that, beside the dor- 

 mouse {Myojous glis, Desm.) the garden dormouse {M. nifela,) 

 and the common dormouse (M. avellanarius,) &c. which hy- 

 bernate, are found the rat, the mouse, the squirrel, and twenty 

 animals of the same kind which do not hybernate ; — that, on the 

 other hand, hybernating animals occur indiscriminately in the 

 most diff*erent families in the insectivorous tribe, as the hedge- 



