SERUM-ALBUMIN, SERUM-GLOBULIN. 73 



(a) Serum-albumin C 78 H 120 N 20 SO 24 from 3 to 4 Per Cent. Its per- 

 centage-composition is C 53.1, H 7.1, N 15.9, S 1.9, O 22, Ash 0.22. Its 

 coagulation-temperature is from 51 to 53 C.; its specific rotatory power 

 61. In the horse and the rabbit it crystallizes in hexagonal prisms, 

 with a pyramid upon one side. The crystals are doubly refracting, 

 up to i cm. in length, and are coagulable by heat. 



It is a remarkable fact that serum-albumin is absent from the blood of 

 starving snakes and it makes its appearance only after feeding. 



(b) Serum-globulin also known as fibrino plastic substance or para- 

 globulin and also as serum-casein from 2 to 4 per cent. If magne- 

 sium sulphate in substance is added to serum to the point of saturation, 

 serum-globulin is precipitated at a temperature of 35 C. It is washed 

 upon a filter with concentrated solution of magnesium sulphate. It is 

 soluble in a 10 per cent, solution of sodium chlorid, and coagulates at a 

 temperature of from 69 to 75 C. Its specific rotatory power is 47.8, 

 and its formula is C 117 H 174 N 3 oSO 38 . 



After precipitation of the serum-globulin from the serum by means of mag- 

 nesium sulphate the serum-albumin is precipitated by further saturation with so- 

 dium sulphate. Neutral ammonium sulphate, added to the point of saturation, 

 precipitates all of the proteids of the blood-serum, arid also those of egg- albumin 

 and of milk ; further, propeptone, but not peptones. Globulin can be precipitated 

 also by dialysis of the serum, as it is insoluble in solutions free from salt. 



During hunger the amount of globulin increases, while that of albumin dimin- 

 ishes. After abstraction of blood the amount of globulin in the blood increases. 

 Paraglobulin occurs also in erythrocytes, as well as in the fluids of the connective 

 tissue and the cornea. According to von Jaksch, 100 cu. cm. of blood contain 

 22.62 grams of albumin, while an equal amount of serum contains more than 8 

 grams. The latter figure varies under pathological conditions. 



Fats from o.i to 0.2 Per Cent. Neutral fats stearin, palmitin, 

 olein occur in the form of minute microscopic droplets, whose presence 

 often renders the serum of a milky turbidity after abundant ingestion 

 of fat and also of milk. They are more abundant during hunger and 

 in drunkards. There occur, besides, soaps, lecithin, and its decompo- 

 sition-product, glycerin-phosphoric acid, and cholesterin. Hiirthle 

 found cholesterin oleate and palmitate 0.17 per cent. According to 

 Hanriot a ferment, known as lipase, occurs in blood and which breaks 

 up neutral fat into glycerin and fatty acids. Lipase is found also in the 

 pancreas and in the liver, and traces also in some other parts of the 

 body. 



A certain amount of grape-sugar from o.i to 0.15 per cent., some- 

 what more in the blood of the hepatic veins, derived from the liver and 

 the muscles and increased after loss of blood ; some glycogen increased 

 in cases of diabetes; a trace of animal gum, a reducing substance, 

 insusceptible of fermentation and soluble in ether, jecorin, which is a 

 combination of dextrose and lecithin ; a dextrose-forming diastatic fer- 

 ment, inactive at a temperature of 65 C. For a discussion of the sugar- 

 destroying power of the blood reference may be made to the section on 

 the liver. 



The amount of sugar in the blood is increased by absorption of sugar from 

 the intestinal tract, and in greatest degree in the blood of the portal and hepatic 

 veins. It is increased also in arterial blood, although here it is rapidly changed. 



For purposes of demonstration blood is coagulated by boiling after addition of 

 sodium sulphate, and the amount of sugar in the expressed fluid is determined 

 with the aid of Fehling's solution. Pavy digested the blood thrice successively 



