CHEMICAL COMPOSITION OF MUSCLE-SEKUM. 



463 



specks, similar to the fibrin of blood, appear in the jelly, and as these begin to con- 

 tract, they squeeze out of the jelly an acid "muscle-serum." [Halliburton finds 

 that the muscles of warm-blooded animals yield a similar muscle-plasma.] Cold 

 prevents or delays the coagulation of the muscle-plasma ; above 0, coagulation 

 occurs very slowly, and the rapidity of coagulation increases rapidly as the tempera- 

 ture rises, while coagulation takes place very rapidly at 40 C. in cold-blooded 

 animals, or at 48 to 50 C. in warm-blooded muscles. The addition of distilled 

 water or an acid to muscle-plasma causes coagulation at once. The coagulated 

 proteid, most abundant in muscle, and which arises from the doubly refractive 

 substance, is called "myosin" (W. Kiihne). 



Myosin. It is a globulin ( 245), and is soluble in strong (10 per cent.) solution of common 

 salt, and is again precipitated, from such a solution by dilution with water, or by the addition 

 of very small quantities of acids (0 - l to 02 per cent, lactic or hydrochloric acid). It is soluble 

 in dilute alkalies or slightly stronger acids (0*5 per cent, lactic or hydrochloric acid), and also 

 in 13 per cent, ammonium chloride solution. [The more myosin is freed from salts (especially 

 of calcium) by washing, the more insoluble does it become, both in saline solutions and weak 

 hydrochloric acid. When once precipitated from its solution, it can be redissolved, reprecipi- 

 tated, and again undergo coagulation a second or even a third time [Halliburton).'] Like fibrin, 

 myosin rapidly decomposes hydric peroxide. When treated with dilute hydrochloric acid and 

 heat, it is very rapidly changed into syntonin ( 245). Myosin may be extracted from muscle 

 by a 10 to 15 per cent, solution of NH 4 C1, and if it be heated to 65, it is precipitated again 

 (Danieleivsky). Danielewsky succeeded in partly changing syntonin into myosin by the action 

 of milk of lime and ammonium chloride. Myosin occurs in other animal structures (cornea), 

 nay, even in some vegetables (0. jasse). 



Muscle-serum, according to Kiihne, still contains three proteids (2'3 to 3 per 

 cent.), viz. : 1. Alkali-albuminate, which is precipitated on adding an acid, even 

 at 20 to 24 C. 2. Ordinary serum-albumin, 1*4 to 1-7 per cent. ('32, a), which 

 coagulates at 73 C. 3. An albuminate which coagulates at 47 C. 



[Halliburton finds, however, the following proteids in muscle-plasma. 



Although the first two go to form the clot of muscle or myosin, paramyosinogen is 

 not essential for coagulation. Besides these bodies there are haemoglobin and 

 also myo-hsematin, which is not identical with the blood-pigment. It can be ex- 

 tracted by ether from muscle (e.g., the breast muscle of a pigeon), whereby the ether 

 becomes red. It can exist in an oxidised and reduced condition (MacMumi).] 



The other chemical constituents of muscle have been referred to in treating of 

 flesh ( 233). 1. Muscle-ferments. Briicke found traces of pepsin and peptone 

 in muscle-juice, [the latter is denied by Halliburton] ; Piotrowsky, a trace of a 

 diastatic ferment. [When muscle becomes acid, as in rigor mortis, the pepsin at a 

 suitable temperature (35 to 40 C.) acts on the proteids, and albumoses and peptones 

 are formed. Halliburton found a myosin-ferment which has the characters of an 

 albumose. 2. In addition to volatile fatty acids fformic, acetic, butyric), there are 

 two isomeric forms of lactic acid (C 3 H 6 3 ) present in muscle with an acid reaction : 

 (a) Ethylidene-lactic acid, in the modification known as right rotatory sarcolactic 

 or paralactic, acid, which occurs only in muscles, and some other animal structures. 

 (6) Ethylene-lactic acid in small amount ( 251, 3, c). It was formerly assumed 

 that lactic acid is formed by fermentation from the carbohydrates of the muscle 

 (glycogen, dextrin, sugar), and Maly has observed that paralactic acid is occa- 

 sionally formed when these bodies undergo fermentation. According to Bohm, 



