48 THE CIRCULATING LIQUIDS OF THE BODY 



nbrinogen in clotting) is also present. Ferments which cause 

 hydrolysis of proteins and carbohydrates, a ferment (lipase) which 

 acts upon fats, and certain oxidizing ferments (oxydases), have also 

 been demonstrated. The chemical nature of the bodies which 

 confer on serum or plasma its specific haemolytic, agglutinating, 

 precipitating, and bactericidal properties has not been definitely 

 determined. 



The quantitative composition of serum, especially as regards the 

 inorganic salts, is remarkably constant in animals of the same species, 

 and even in animals of different species belonging to the same, or to 

 not very widely separated, natural groups. In cold-blooded animals 

 the serum-albumin is scantier than in mammals, the globulin relatively 

 more plentiful. 



Serum-albumin belongs to the class of native albumins. It has 

 been obtained in a crystalline form from the serum of horse's blood. It 



Fig. ii. Perspective View of Vivi-Diffusion Apparatus (Abel). This form of the 

 apparatus contains sixteen tubes. A, arterial cannula; B, venous cannula; 

 C, side tube for introduction of hirudin; D, inflow tube; E, outlet tube for the 

 blood; F, G, supporting rod attached at H and K to branched V-tubes; L, burette 

 for hirudin; M, N, tube for filling and emptying liquid in outer jacket; O, air 

 outlet; P, dichotomous branching-point of inflow tube; Q and R, quadruple 

 branching-points of the same ; S, S, wooden supports; T, thermometer. At 

 each of the points H and K the blood is collected from four tubes into one, 

 bending round to the back, and there redividing into four return flow tubes. 

 Arrows show the direction of the flow. 



is soluble in distilled water, and is not precipitated by saturating its 

 solutions with certain neutral salts. Heated in neutral or slightly 

 acid solution, it coagulates first at 73, then at 77, then at 84 C. 

 Although this is not of itself sufficient proof, there is other evidence 

 that it consists of a mixture of proteins. 



Serum-globulin, also called paraglobulin, belongs to the globulin 

 group of proteins. When heated, it coagulates at about 75 C. (p. 9). 

 It is insoluble in distilled water, and is precipitated by saturation with 

 such neutral salts as magnesium sulphate, or by half -saturation with 

 ammonium sulphate. It appears that, as thus obtained, it is not a 

 single substance, but a mixture of at least two proteins eu-globulin, 



