FUNCTIONS OF THE CONSTITUENTS OF BLOOD. 125 



substantiated : they are carbonic acid, oxygen, and nitrogen. Gases of the 

 He found that this liquid can absorb once and a half its vol- blood - 

 ume of carbonic acid, and that in arterial blood the proportion of that 

 acid to oxygen is as 16 to 6, in venous as 16 to 4. That the oxygen 

 is very loosely retained is shown by the circumstance that it may for 

 the most part be removed by exposure in a vacuum. The other gases 

 may be withdrawn by a stream of hydrogen. 



At a temperature of 98, water absorbs scarcely one per cent, of its 

 volume of oxygen gas, but the blood can take up from 10 to 13 times as 

 much. This is accomplished by the coloring material. The amount is 

 independent of variations in the pressure of the air, which would not be 

 the case if the gas were received into the circulating fluid by mere solu- 

 tion. This is the opinion of Liebig, by whom it is regarded as being to 

 some extent substantiated by the fact that the respiration is accomplished 

 with nearly the same result, so far as the absorption of oxygen is con- 

 cerned, at considerable heights above and at the level of the sea, and that 

 no more oxygen is received from an atmosphere very rich in that gas 

 than from the ordinary air. However correct this view may be, the facts 

 cited in its support are very far from being undeniable. 



The preceding chemical examination of the special constituents of the 

 blood leads us next to consider the general functions of this liquid in the 

 aggregate. 



In this general sense, the blood discharges the following offices. Its 

 albumen has the duty of giving origin to all the plastic tis- General state 

 sues of the system. From it, for example, by cell action, as ment of the 

 explained in treating of lacteal absorption, fibrin arises theliiffkrent 

 fibrin, which is used for the renovation and repair of the mus- constituents of 

 cular tissues. The discs have a relation with the function of 

 respiration; they obtain oxygen in the pulmonary circulation, and carry 

 it through the system. They contribute, moreover, to the development 

 of muscular fibre, and also nervous material, and this not alone as regards 

 the coloring matter of those tissues. The fats are necessary in the pro- 

 duction of fibrin and for the nuclei of cells ; but, besides these histoge- 

 netic relations, they eventually, with the exception of liver-fat, undergo 

 oxidation, and so minister to the support of a high temperature. Of the^ 

 saline substances, common salt promotes digestion by aiding in the prep- 

 aration of gastric and pancreatic juices ; the phosphate of soda enables 

 the plasma to hold carbonic acid in solution, and carry it to the lungs. 



It is interesting to observe the limits of variation which the blood may 

 present in disturbed or diseased conditions. In inflammations, the fibrin 

 may increase fourfold ; in typhoid fevers it may diminish to less than 

 one half, and from these variations special results may arise. Thus 

 diminution of its fibrin disposes the blood to preternatural oozing or fa- 



