CHEMICAL COMPOSITION OF BLOOD-PLASMA. 409 



table, taken from Abderhalden,* and showing the composition of 

 dogs' blood, may serve as an example: 



The same constituents in much the same proportions are found 

 in the blood of all the mammalia examined. The amount of proteid 

 in the serum is greater in some cases than in others, in the dog, 

 for instance, according to Abderhalden's analyses, the proteid 

 amounts to only 6 per cent., while in the horse it may be 7 or 8 per 

 cent. So also there are small variations in the amount of choles- 

 terin, sugar, and other constituents, but, on the whole, the composi- 

 tion of the liquid part of the blood, blood-serum or blood-plasma, 

 is remarkably uniform so far as chemical analyses go. We know, 

 however, that the physiological properties of mammalian sera may 

 be very different indeed; that the serum of a dog, for instance, will 

 kill a rabbit when injected into its vessel. Such physiological dif- 

 ferences as this, however, depend upon constituents which can not 

 be defined or determined by chemical means. The chemical com- 

 position of the blood-serum differs from that of the red corpuscles in 

 a number of respects in addition to the presence of hemoglobin in 

 the latter. The corpuscles contain no sugar nor fat, a larger amount 

 of cholesterin, lecithin, phosphoric acid, and potassium, and less 

 sodium and chlorin. The red corpuscles of different mammalia 

 show a remarkable variation in the amount of potassium salts 

 contained. Thus, according to Brandenburg, 1000 parts by weight 

 of the red corpuscles contain the following amounts of K 2 O in 

 different mammalia: Cat, 0.258: dog, 0.257; man, 4.294; horse, 

 4.957; rabbit, 5.229. 



* "Zeitschrift f. physiologische Chemie," 25, 88, 1898. 



