MUSCLE AND NERVOUS TISSUES 161 



In a day or two crystals of creatine tinged with myohsematin separate out. 



(b) Take an aqueous extract of muscle, like Liebig's extract or beef-tea ; 

 add baryta water to precipitate the phosphates, and filter. Remove excess 

 of bary-ta by a stream of carbonic acid ; filter off the barium carbonate and 

 evaporate the filtrate on the water-bath to a thick syrup. Set it aside to cool, 

 and in a few days crystalline deposits of creatine wiU be found at the bottom 

 of the vessel. These are washed with alcohol and dissolved In hot water. 

 On concentrating the aqueous solution crystals once more separate out, 

 which may be still further purified by recrystalli sation. 



Creatinine can be obtained from meat extracts by Johnson's method (see 

 pp. 124, 125) : mdeed, Johnson states it is usually more abundant than crea- 

 tine, and that the same is true for fresh meat. 



Note. — The exercises on muscle plasma described in this lesson have 

 been in the main derived from my own investigations on the subject 



Fig. 62.— a desiccator. (Gscheidlen.) 



(' Joum. of Physiol.,' viii. p. 133, ' Chemical Physiology and Pathol.,' Chap. 

 XX.). The same subject has been recently taken up by v. Fiirth (' Arch. 

 Exp. Path. u. Pharm. 1895,' vol. xxxvi. p. 231). His nomenclature of the 

 proteids is somewhat different from mine, but on main questions we are 

 in substantial agreement — ^•iz. that in the muscle plasma there are two 

 principal proteids ; these become changed, and so lead to the formation of 

 the muscle clot, or myosin-fibrin as he terms it. He uses physiological saline 

 solution to extract the muscle plasma, and this coagulates spontaneously on 

 standing ; paramyosinogen (v. Fiirth's myosin) passes directly into the con- 

 dition of myosin-fibrin ; but myosinogen (v. Fiirth's myogen) first passes into 

 a soluble condition (coagulable by heat at the remarkably low temperature of 

 40° C.) before the myogen-fibrin separates out. The myo-albumin which 

 occurs in minute amount is probably serum albumin fi-om adherent blood or 

 lymph. The main points of difference between us are (1) he looks upon 

 myosinogen as not being a true globulin, though like a globulin in some of its 

 characters ; (2) myo-globulin is not a separate proteid, but only some myosino- 

 gen which has escaped coagulation. (3) The phenomenon I have termed re- 

 coagulation of muscle plasma he looks upon as being merely a reprecipitation 



M 



