APP.] CHEMICAL BASIS OF THE ANIMAL BODY. 715 



selves undergoing no change, soon become covered with babbles of oxygen; and 

 guaiacum is turned blue by fibrin in presence of hydrogen dioxide or ozonised tur- 

 peutine. 



Preparation. By vigorously stirring blood with a bundle of twigs 

 and then washing with water until it is quite white. If required per- 

 fectly pure and colourless it should be prepared from plasma free from 

 corpuscles. If the blood, before stirring, be diluted with an equal bulk 

 of water, the subsequent, washing of the fibrin is much facilitated, and 

 it may readily be obtained quite white. Any adherent fats may be re- 

 moved by aether. 



When globulin, myosin, and fibrin are compared each with the other, 

 it will be seen that they form a series in which myosin is intermediate 

 between globulin and fibrin. Globulin is excessively soluble in even 

 the most dilute acids and alkalis ; fibrin is almost insoluble in these ; 

 while myosin, though more soluble than fibrin, is less soluble than 

 globulin. Globulin again dissolves with the greatest ease in a very 

 dilute solution of sodic chloride. Myosin, on the other hand, dissolves 

 with difficulty ; it is much more soluble in a 10 per cent, than in a one 

 per cent, solution of sodic chloride; and even in a 10 per cent. 

 solution the myosin can hardly be said to be dissolved, so viscid is the 

 resulting fluid and with such difficulty does it filter. Fibrin again 

 dissolves with great difficulty and very slowly in even a 10 per cent, 

 solution of sodic chloride, and in a one per cent, solution it is 

 practically insoluble. When it is remembered that fibrin and myosin 

 are, both of them, the results of coagulation, their similarity is in- 

 telligible. Myosin is in fact a somewhat more soluble form of fibrin, 

 deposited not in threads or filaments but in clumps and masses. 



CLASS V. Coagulated Proteids. 



These are insoluble in water, dilute acids and alkalis, and neutral 

 saline solutions of all strengths. In fact they are really soluble only in 

 strong acids and strong alkalis, though prolonged action of even dilute 

 acids and alkalis will effect some solution, especially at high tempera- 

 tures. During solution in strong acids and alkalis a destructive decom- 

 position takes place, but some amount of acid- or alkali-albumin is 

 always produced. 



Very little is known of the chemical characteristics of this class. 

 They are produced by heating to 70 C., solutions of egg- or serum- 

 albumin, globulins suspended in water or dissolved in saline solutions ; by 

 boiling for a short time fibrin suspended in water or dissolved in saline 

 solutions, or precipitated acid- and alkali-albumin suspended in water. 

 They are readily converted at the temperature of the body into peptones, 



