98 THE CHEMISTRY OF THE TISSUES AND ORGANS. 



of the nature of nucleo-proteids. He found that they are not. He was indeed 

 able to obtain no nucleo-proteid at all from muscle. Pekelharing 1 has taken 

 up the latter question, and by an improved method discovered that muscular 

 tissue does contain a small amount of nucleo-proteid. He points out that on 

 gastric digestion small quantities of nuclein are soluble, if the amount of 

 hydrochloric acid present exceeds O'l per cent. Whitfield used water as an ex- 

 tracting agent for any possible nucleo-proteid. Pekelharing points out that the 

 water will soon become acid from sarcolactic acid, and uses dilute (0*15 per cent.) 

 sodium carbonate solution instead. From such an extract the nucleo-proteid 

 can be precipitated by acetic acid. From 543 grms. of flesh he obtained 2 grms. 

 of nucleo-proteid. This substance produces intravascular clotting, and contains 

 0*7 of phosphorus. The nuclein split off from it contains 3*5 per cent, of 

 phosphorus, and on decomposition yields alloxuric bases, especially xanthine 

 and guanine. Hypoxanthine and adenine were not found. Kossel 2 also failed 

 to get adenine from muscle. 



An important research on muscle plasma and its proteids has lately 

 been published by v. Ftirth. 3 He obtained the plasma from blood-free 

 muscles by extracting them with physiological saline solution. This 

 extract coagulates spontaneously, and the clotted proteid formed he calls 

 myogen fibrin or myosin fibrin. The proteids in the muscle plasma he re- 

 duces to three, namely, paramyosinogen, 17 to 22 per cent, of the total pro- 

 teid ; myosinogen or myogen, 77 to 83 per cent., and traces of an albumin. 4 



My work is confirmed in its main point, namely, that there are two 

 proteids in the muscle plasma, paramyosinogen and myosinogen, which 

 enter into the formation of the muscle clot ; the action of a specific 

 ferment to bring about this change was not specially investigated. The 

 principal new fact made out is, that paramyosinogen passes into the 

 condition of myosin fibrin directly ; whilst in the passage of myosinogen 

 into the state of myogen fibrin, there' is an intermediate soluble stage 

 coagulable by heat, at the remarkably low temperature t)f 40 C. 5 



Paramyosinogen is described as a typical globulin, and is regarded as 

 identical with Kiihne's myosin which he obtained by dropping muscle plasma 

 into water. Myosinogen is described as differing from a globulin in some 

 particulars, and is spoken of as a proteid sui generis. Myoglobulin is not 

 regarded as a separate proteid, but as part of the myosinogen which has 

 escaped coagulation. The phenomenon regarded by Chittenden and myself as 

 re-coagulation of myosin is considered to be a simple re-precipitation of globulin. 

 Whitfield's work on the absence of peptones and proteoses is confirmed. 



The muscle plasma from fishes' and crabs' muscle contains another proteid, 

 called myo-proteid. It gives the usual proteid reactions, and is readily digested 

 by gastric juice ; though precipitated by a removal of the salts by dialysis, it 

 is not coagulable by heat. It is precipitable by acetic acid, but is neither a 

 mucin nor a nucleo-proteid. 



In his second paper, v. Furth treats of (1) the properties (solubilities, 



1 Ztschr.f. physiol. Chem., Strassburg, 1896, Bd. xxii. S. 245. 



2 Ibid., 1886, Bd. x. S. 248. 



3 Arch. f. exper. Path. u. Pharmakol., Leipzig, 1895, Bd. xxxvi. S. 231; also ibid., 

 1896, Bd. xxxvii. S. 389. 



4 J. H. Milroy (Arch. f. Hyg., Miinchen u. Leipzig, 1896, Bd. xxv. S. 154) has also made 

 quantitative estimations of the various muscle proteids coagulable at different temperatures. 



5 If the reader refers to my memoir on "Muscle Plasma," he will find, on p. 186, that I 

 accidentally noted this fact, though I failed to appreciate its meaning. In frogs' muscle 

 plasma there is a considerable amount of this soluble myogen fibrin in a "preformed" 

 condition (v. Furth). The separation of the muscle proteids by fractional heat coagulation 

 fits in exactly with Brodie and Richardson's work on heat rigor ; as the temperature of a 

 muscle is raised, successive shortenings occur at the coagulation temperature of each 

 proteid (Proc. Roy. Soc. London, 1897, vol. Ixi. p. 77). 



