18 



THE BLOOD. 



phorizcd fats are more abundant in the globules, while the fatty acids are 

 more abundant in the plasma. The salts of potassium exist almost entirely 



in the corpuscles, and the sodium salts 

 are four times more abundant in 

 the plasma than in the corpuscles 

 (Schmidt). In addition to the nutri- 

 tive matters, the blood contains urea, 

 cholesterine, sodium urate, creatine, 

 creatinine, and other substances, the 

 characters of which are not yet fully 



t determined, belonging to the class of 



A'";'\ \ ^Jjk excrementitious matters. Their con- 



\^/ A jl\ sideration comes more appropriately 



under the head of excretion. 



The following table gives approxi- 

 mately the quantities of the differ- 

 ent constituents of the blood-plasma. 

 These may be divided into the follow- 

 ing classes : 1. Inorganic constituents; 

 2. Organic saline constituents; 3. Or- 

 ganic non - nitrogenized constituents; 

 4. Excrementitious constituents ; 5. Or- 

 ganic nitrogenized constituents. This 

 table will be taken as a guide for the 

 study of the individual constituents 

 of the blood-plasma. As regards gases, 

 in addition to carbon dioxide, which 

 is classed with the excrementitious con- 

 stituents, the blood contains oxygen, nitrogen and hydrogen. The nitrogen 

 and hydrogen are not important, and the relations of oxygen will be fully 

 considered in connection with the physiology of respiration. Most of the 

 coloring matter of the blood exists in the red corpuscles, which contain a 

 peculiar substance that has already been considered in connection with the 

 chemical constitution of these bodies. 



In studying the composition of the blood, as well as the composition of 

 food, the tissues, secreted fluids etc., it is convenient to divide its constituents 

 into classes, and this has been done in the simplest manner possible. 



It is evident, the blood receiving all the products of disassimilation as 

 well as the nutritive matters resulting from digestion, that there should be 

 a division of its constituents into nutritive and excrementitious. The ex- 

 crementitious matters are the products of disassimilation of the organism, 

 which are taken up by the blood or conveyed to the blood-vessels by the 

 lymphatics, exist in the blood in small quantity, and are constantly being 

 separated from the blood by the different excreting organs. Their constant 

 removal from the blood is the explanation of the minute proportion in which 

 they exist in this fluid. 



FIG. 9. Crystallized hcemaglobine (Gautier). 

 a, 6, crystals from the venous blood of man ; c, 

 blood of the cat : d, blood of the Guinea pig: 

 e, blood of the marmot ; /, blood of the squir- 

 rel. (Gautier.) 



