THE CHEMICAL COMPOSITION OF THE BLOOD 



169 



accompanying table shows the composition of dog's blood as determined by 

 Abderhalden. ^ In another table are given the values for the blood of the horse. 



THE COMPOSITION OF HORSE'S BLOOD 



Sodium chlorid is the chief salt of the serum. It forms 60 per cent, of the ash, 

 while sodium carbonate constitutes about 30 per cent, of it. Traces of the chlo- 

 rids and phosphates of potassium, sodium and calcium are also present. The chief 

 salt of the corpuscles is potassium phosphate, while that of the plasma is sodium 

 chlorid. In fact, it has been stated that the latter is entirely wanting in the cor- 

 puscles of some animals. The potassium content of different corpuscles fluctuates 

 considerably. Chlorin exists in all types of blood, but in greater amounts in the 

 serum than in the corpuscles. lodin is found only in the serum, while iron appears 

 principally in the erythrocytes, but in small quantities also in the leukocytes. 

 Traces of manganese, lithium, copper, and lead have also been obtained. 



Traces of fats, cholesterin, lecithin, dextrose, urea, and other nitrogenous 

 extractives are also present in the serum. The fats in the corpuscles average 

 0.6 per cent., but this figure may be decreased or increased by feeding. Thus, an 

 increase of ten times the normal value has been obtained by this means in geese, 

 while, in diabetic lipemia, as high a value as 18 per cent, has been found. The 

 fats circulate in the blood in very fine subdivision, the individual globules becom- 

 ing so numerous at times that a distinct oily or milky appearance is imparted to 

 the blood or to the serum derived from it. 



Cholesterin and lecithin are found chiefly in the erythrocytes, nine-tenths of 

 the solids of these cells being formed by hemoglobin and one-tenth by the stroma. 

 In addition to these two substances, the stroma also embraces proteins and salts. 



The amount of sugar in the blood varies between 0.1 and 0.15 per cent, and, 

 although somewhat independent of the character of the food ingested, may be 

 greatly increased by feeding. As has been pointed out by Claude Bernard, ^ sugar 



1 Zeitschr. fur Physiol. Chemie, xxv, 1898, 88. 



2 Lecons sur la diabete, Paris, 1877. 



