88 ANIMALCULA OF INFUSIONS. |« 



rhe atmofphere at the time ; and in fifteen mi- 

 nutes, that of the other raifed it to 93° (i). 



Some 



elaborate and learned differtation on Fox-tail, (Covetta) 

 and ammunition bread. 



( I ) It will be obferved, tliat, in the courfe of this work, 

 much isfaid of cold and warm blooded animals, and fome 

 important conclufions thence deduced. Notwithftanding 

 all that has been written on animal heat, the caufe is un- 

 doubtedly very obfcure. Experiments and reafoning have 

 neither fufficiently coincided, nor been fo generally adopt- 

 ed, as to entitle us to form pofitive opinions on the fub- 

 jed, more efpecially when philofophers do not agree 

 whether the living body has the property of producing 

 heat or cold. 



Amphibia, reptiles, fiflies, infedls and worms, are ge- 

 nerally believed to have cold blood. However, there are 

 experiments on all but the lad that feem to indicate a 

 principle of internal heat independent of the atmofphere ; 

 fo that the thermometer will afcend when removed from 

 the open air into their bodies. Yet many naturalifts de- 

 ny that they have any principle of heat ; and think the 

 temperature of their bodies muft always be exadly the 

 fame as that of the furrounding medium. But, in my 

 opinion, fufficient accuracy in experiment has been ne- 

 gleded, and due attention has not been paid to the ftate 

 of the medium where the animals previoully were. A few 

 experiments which I have made on the fubjeft, even with 

 thpfe precautions, have been difcordant ; one thing how- 

 ever 



