CHEMICAL BASIS OF THE ANIMAL BODY. 31 



Globulins to which the name of myosin is applied are described as 

 occurring in vegetable protoplasm 1 and in the cells of the liver 2 . 



Myosin is readily digested by pepsin, more slowly by trypsin. The 

 primary products arising from the digestive action of the former 

 enzyme have been studied by Kiihne and Chittenden 3 . 



6. Globin. 



When haemoglobin is allowed to undergo decomposition spon- 

 taneously by exposure to the air an insoluble proteid is obtained of 

 which very little is known, but to which the name of globin was given 

 by Preyer 4 . It appears to be perhaps an outlying member of the 

 globulin class of proteids, but unlike a true globulin is scarcely soluble 

 in dilute acids and imperfectly soluble in alkalis and solutions of 

 sodium chloride. It is converted into acid and alkali-albumin by the 

 action of strong acids and alkalis respectively, and is stated to yield no 

 trace of ash on incineration. 



CLASS IV. Fibrin. 



This proteid is ordinarily obtained by ' whipping ' blood with a 

 bundle of twigs until clotting is complete ; the fibrin which adheres to 

 the twigs is then washed in a current of water until all the haemoglobin 

 of the entangled corpuscles is removed and it is now quite white. The 

 washing is greatly facilitated if the fibrin is very finely chopped before 

 it is washed, and if it is frequently kneaded and squeezed with the 

 hand during the washing. In this way it may be obtained quite white 

 in a few hours. The washing is also much facilitated if the blood is 

 mixed with an equal bulk of water before it is whipped. It is obvious 

 that fibrin prepared by the above method must be in an extremely 

 impure condition, for it contains a not inconsiderable admixture of the 

 remains of the white corpuscles and the stromata of the red 5 . It can 

 only be prepared pure during the clotting of either filtered or centri- 

 fugalised iced-plasma or salt-plasma, or by the action of purified 

 fibrin-ferment on pure fibrinogen. In accordance with this, fibrin as 

 ordinarily obtained leaves a variable amount of granular residue which 

 contains phosphorus during its digestion by pepsin. No such residue 

 is observed when fibrin from filtered plasma is digested with pepsin 

 (see below p. 41), but in no other essential respect does the one fibrin 

 differ from the other. 



1 Weyl, Zt.physiol. Chem. Bd. i. (1877), S. 96. 



2 Plosz, Pfliiger's Arch. Bd. vn. (1873), S. 377. 



3 Zt.f. Biol. Bd. xxv. (1889), S. 358. See also Chittenden and Goodwin, Jl. of 

 Physiol. Vol. xn. (1891), p. 34. 



4 "Die Blutkrystalle," Jena, 1871, S. 166. 



5 Hammarsten, Pfliiger's Arch. Bd. xxn. (1880), S. 481 ; xxx. (1883), S. 440. 



