366 LIQUID PARTS OF ANIMALS. 



Dr Davy has found that fresh blood, when agitated with oxy- 

 gen gas or common air, absorbs a little oxygen gas, while the 

 thermometer rises one or two degrees, without giving out any 

 carbonic acid gas. He could not find that blood gave out car- 

 bonic acid gas when agitated with other gases ; but it absorbed 

 more than its own volume of carbonic acid. * 



It is not easy to draw any inference from these contradictory 

 experiments. 



II. PROPORTION OF THE CONSTITUENTS OF BLOOD. 



Having described the different substances which enter into 

 the constitution of blood, let us now endeavour to state the va- 

 rying proportions of each in different circumstances. 



1. When blood is left at rest it divides into two portions, the 

 serum and crassamentum. The proportion between these two 

 differs greatly under different circumstances. 



(1.) There is a considerable diversity in the specific gravity of 

 serum, as will appear from the following table : 



Sp. gravity. 



1-027 to 1-029 Berzelius. 



1-025 Marcet, Med.-Chir. Trans, iii. 363. 



1-0287 By my trials. 



1-0262 Richardson. 



1-0264 Arterial. \ ^ de Sciences Natur _ g 



1-0257 Venous. J 



1-047 to 1-050 Dr Davy, Phil. Trans. 1814, p. 591. 



1-020 of a calf after three bleedings. 1 Andrews, Records of 



1-017 do. after four bleedings. / Science, i. 53. 



If we leave out the determinations of Dr Andrews, because the 

 blood was not in a normal state, the mean specific gravity of se- 

 rum is 1-0296. And if we leave out the determination of Dr 

 Davy, which deviates too far from the rest, the mean specific gra- 

 vity of serum will be 1-0265. 



(2.) The mean specific gravity of the crassamentum, accord- 

 ing to Dr Jurin, is l-245.f 



(3.) The crassamentum cannot be freed completely from the 

 serum. It consists essentially of the globules of the blood ; and 

 these globules, according to the experiments of Lecanu, are com- 

 posed of fibrin, hematosin, and albumen. 



(4.) The following table exhibits the proportions between the 



- Phil. Trans. 1834, p. 283. f Haller's Physiology, ii. 41. 



