p4 ANIMALCULA OF INFUSIONS. J; 



pears to me, Is the only and immediate caufe of 

 lethargic fleep in the latter, I do not fee why it 

 , may not alfo be extended to the former. 



The fame degree of cold does not occafion tor- 

 pidity in all the animals fubjeft to it. Very lit- 

 tle is neceflary for fome ; others require confidera- 

 bly more ; and others an exceffive degree ( i ). 

 "What we defign temperate, which is fo mild to 

 our fenfations, occafions torpidity in dormice ; 

 a little more afFedts bees, fnakes, vipers, and 

 many fpecies of bats. What afFed:s frogs, toads, 

 newts, and others, approaches freezing, but this 

 is far from operating on marmots, as they re- 

 quire 1 1 degrees below freezing (2), The dif- 

 ference 



( 1 ) Reailmur Memoires fur les Infeclcs. 



(2) At difFerent feafons, however, the fame cold feems 

 to produce diiFerent effefls. On the 18 of July, when 

 the heat is generally between 60^ and 70**, I cooled the 

 •water with fix Hydrachnae down to 38". They all funk 

 to the bottom, and remained completely torpid. In ge- 

 neral, they yielded to 42^ or 40^, except one, called, by 

 MuUer, a variety of the Papillator (but apparently con- 

 fliiuting a particular fpecies in Scotland), which refifted 

 38" a Inng time, and then funk down along with the reft. 

 All revived at a moderate heat. 



On the 5 of December, I took five hydrachnae from 

 water at about 44°, and put them into water at 36°. 

 They became more languid. The thermometer gradual- 



ly 



