CASEIN SYNTONIN MYOSIN. 



23 



a soft, yet tough, elastic, and opaque-white substance, which 

 consist of fibrin, impure, with a mixture of fatty matter, lymph- 

 corpuscles, shreds of the membranes of red blood-corpuscles, 

 and some saline substances. Fibrin somewhat purer than this 

 may be obtained by stirring blood while it coagulates, and 

 collecting the shreds that attach themselves to the instrument, 

 or by retarding the coagulation, and, while the red blood- 

 corpuscles sink, collecting the fibrin unmixed with them. But 

 in neither of these cases is the fibrin perfectly pure. 



Chemically, fibrin and albumen can scarcely be distin- 

 guished ; the only difference apparently being that fibrin con- 

 tains 1.5 more oxygen in every 100 parts than albumen does. 

 Mr. A. H. Smee has, indeed, apparently converted albumen 

 into fibrin, by exposing a solution to the prolonged influence 

 of oxygen. Nearly all the changes, produced by various 

 agents, in coagulated albumen, may be repeated with coag- 

 ulated fibrin, with no greater differences of result than may 

 be reasonably ascribed to the differences in the mechanical 

 properties of the two substances. Of such differences the prin- 

 cipal are, that fibrin immersed in acetic acid swells up and 

 becomes transparent like gelatin, while albumen undergoes 

 no such apparent change ; and that deutoxide of hydrogen is 

 decomposed when in contact with coagulated fibrin, but not 

 with albumen. 



Casein, which is said to be albumen in combination with 

 soda, exists largely in milk, and forms one of its most im- 

 portant constituents. 



Syntonin is obtained from muscular tissue, both of the striated 

 and organic kind. It differs from ordinary fibrin in several 

 particulars, especially in being less soluble in nitrate and car- 

 bonate of potash, and more soluble in dilute hydrochloric acid. 



Myosin is the substance which spontaneously coagulates in 

 the juice of muscle. It is closely allied to syntonin ; indeed, 

 in the act of solution in dilute acids, it is converted into it. 



The percentage composition of albumen, fibrin, gelatin, and 

 chondrin, is thus given by Mulder : 



