FATTY MATTERS IN THE BLOOD. 75 



of the brain, and the ordinary saponifiable fats, stearin, olein, 

 and palmitin. A volatile fatty acid is that on which the odor 

 of the blood mainly depends; and it is supposed that when 

 sulphuric acid is added (see p. 56), it evolves the odor by com- 

 bining with the base, with which, naturally, this acid is neu- 

 tralized. According to Lehmann, much of the fatty matter 

 of the blood is accumulated in the red corpuscles. 



These fatty matters are subject to much variation in quan- 

 tity, being commonly increased after every meal in which fat, 

 or starch, or saccharine substances have been taken. At such 

 times, the fatty particles of the chyle, added quickly to the 

 blood, are only gradually assimilated ; and their quantity may 

 be sufficient to make the serum of the blood opaque, or even 

 milk-like. 



As regards the inorganic constituents of the blood the sub- 

 stances which remain as ashes after its complete burning one 

 may observe in general their small quantity in proportion to 

 that of the animal matter contained in it. Those among them 

 of peculiar interest are the phosphate and carbonate of sodium, 

 and the phosphate of calcium. It appears most probable that 

 the blood owes its alkaline reaction to both these salts of 

 sodium. The existence of the neutral phosphate (Na 2 H,PO 4 ) 

 was proved by Enderlin: the presence of carbonate of sodium 

 has been proved by Lehmann and others. 



In illustration of the characters which the blood may derive 

 from the phosphate of sodium, Liebig points out the large ca- 

 pacity which solutions of that salt have of absorbing carbonic 

 acid gas, and then very readily giving it off again when agitated 

 in atmospheric air, and when the atmospheric pressure is di- 

 minished. It is probably, also, by means of this salt, that the 

 phosphate of calcium is held in solution in the blood in a form 

 in which it is not soluble in water, or in a solution of albu- 

 men. Of the remaining inorganic constituents of the blood, 

 the oxide and phosphate of iron referred to, exist in the liquor 

 sanguinis, independently of the iron in the corpuscles. 



Schmidt's investigations have shown that the inorganic con- 

 stituents of the blood-cells somewhat differ from those con- 

 tained in the serum ; the former possessing a considerable pre- 

 ponderance of phosphates and of the salts of potassium, while 

 the chlorides, especially of sodium, with phosphate of sodium, 

 are particularly abundant in the latter. 



Among the extractive matters of the blood, the most note- 

 worthy are Oreatin and Creatinin. Besides these, other or- 

 ganic principles have been found either constantly or gen- 

 erally in the blood, including casein, especially in women 

 during lactation : glucose, or grape-sugar, found in the blood 



