652 PHYSIOLOGICAL CHEMISTRY. 



globin as a solution of blood is gradually neutralized. Tartaric acid, 

 2^^, is the acid used, and the addition of acid is made by means of a 

 specially devised pipette until the two absorption bands become no 

 longer visible through the spectroscope. 



The alkalinity of the blood may be estimated by mixing 5 c.c. of freshly 

 drawn blood with about 45 c.c. of a 0.25 per cent, solution of ammonium 

 oxalate (which prevents coagulation) and titrating this mixture with a |^ solu- 

 tion of tartaric acid, using as an indicator lacmoid paper soaked in a concen- 

 trated solution of magnesium sulphate. 



For clinical purposes, where often but small quantities of blood are avail- 

 able, the following method may be used. The blood is drawn into a capillary 

 pipette up to the mark etched on the stem; the pipette is next tilted to 

 admit a bubble of air into the bore, and then ^ sulphuric acid is drawn in to 

 the mark. The exactly equal volumes of blood and acid thus obtained are 

 transferred to a watch-glass, well mixed, and a drop of the mixture then 

 tested with lacmoid paper. If an acid or alkaline reaction be shown, the 

 operation is repeated with weaker or stronger acid until the resulting mixture 

 is neutral. 



Odor. The peculiar odor of blood, differing widely in different 

 animals, is due chiefly to the presence of certain volatile fatty acids. 

 Addition of sulphuric acid renders the odor more distinct. 



The composition of blood. The following table, taken from Howell, 

 lists the more important constituents of blood-plasma : 



f Fibrin ogen. 



I Paraglobulin. { Euglobulin. 

 Proteins. -< <- Pseudoglobulm. 



Serum-albumin. 

 [ Nucleo-protein. 

 Fats. 

 Sugar. 

 Urea. 



Jecorin. 

 Extractives. ^ Glucuronic acid< 



Lecithin. 

 Cholesterin. 

 Lactic acid. 



Chlorides "| f Sodium. 

 Carbonates I j Potassium. 

 lts ' 1 Sulphates j of -j Calcium. 



Phosphates \ I Magnesium. 



L Iron, 

 f Internal secretions. 



Enzymes. { ^P as ^ 

 Enzymes and unknowns. ^ Glycolase, etc. 



I Immune bodies (amboceptors). 

 Complements. 

 I Opsonins. 



