Chap. 2.] [ 8i ] 



CHAP. It. 



OF THE BLOOD. 



Sanguineous 'and exfanguineous Animals. Warm and co !J Hooded Ani* 

 mah.Semm and Craffamentum. Polypufes. Analyfis of Blood. 

 Lymph. Iron in the Blood. Caufe of the Red Colour. Red Glo- 

 &uIes.~Htirivfon's Experiments. 



TPIIS fluid, which is fo efier.tial to life, varies 

 confiderably in different fpecies of animals. Iri 

 man, and other large animals, it is of a red colour, 

 but in fome fmaller animals the circulating fluid is 

 nearly colourlefs, and therefore fuch animals are called 

 exfanguineous ; though with little propriety, as their 

 circulating fluid appears to anfwer all the purpofes of 

 blood, and there feems no reafon to affirm that nothing 

 can be blood, which is not of a red colour; The molt 

 remarkable difference in the blood of animals, is with, 

 refpeft to the temperature. The blood of man, qua- 

 drupeds, and birds, is hotter than the medium they 

 inhabit^ they are therefore called animals with 

 warm blood. In fiflies and reptiles it is nearly of the 

 temperature of the medium they inhabit ; and thefe 

 are therefore called animals with cold blood. The 

 temperature of the blood, as well as the change of co- 

 lour to a brighter red, which the blood undergoes in 

 pafling through the lungs, will be treated of in a future 

 chapter on refpiration. 



When blood is firft drawn from a vein, it appears 

 to be an homogeneous red fluid : it then confolidates 

 into one uniform mafs ; in a little time a yellowifh 

 watery liquor begins to feparate fronj it, which is more 



VOL. III. G or 



