MUSCLE. 



95 



other cells present. The corpora lutea are coloured by lutein. This is a 

 lipochrome (see p. 20). Tlmdichum l was the first to point out that it 

 is distinct from ha?matoidin, which is also generally present. 



The constituents of eggs are described with the various proteids, 

 etc., of which they are made up. 



MUSCLE. 



Skeletal muscle. A muscle contains, besides the muscular fibres, 

 supporting connective tissue with fat. Each fibre consists of two parts, 

 the sheath or sarcolemma, and the contractile substance which it 

 encloses. The sarcolemma resembles elastin very closely in its 

 solubilities. 2 



The contractile substance is of soft consistency, and contains a large 

 percentage of proteids, and smaller quantities of various extractives and 

 salts. By the use of a press a juice can be squeezed out of perfectly 

 fresh muscles, which is called the muscle plasma. Like blood plasma, 

 this coagulates, and the proteid clot is called myosin; this occurring 

 within the body after death is the cause of rigor mortis. 



Living muscle is alkaline ; but after extreme activity, and after 

 death, the reaction becomes acid ; this is due in part to the development 

 of sarcolactic acid. 



The percentage of water in muscle varies in different animals : 3 



Man . 72 to 74 per cent. 



Ox . .77 



Pig. . 78 



Cat. . 75 

 Fox. 74 



Birds 



70 to 76 per cent. 



80 



82 



Amphibians 76 

 Fishes . 79 

 Crab . 85 

 Pecten 79 80 



In young animals, and during inanition, the percentage of water is 

 greater. 



Human muscle has the following average percentage composition : 



Water 73 -5 per cent. 



Solids 26-5 



Proteids, including sarcolemma, proteids of con- 

 nective tissue, vessels, and pigments . . 18*02 



Gelatin 1*99 



Fat 2-27 



Extractives (creatine, lactic acid, glycogen, etc.) 0*22 

 Inorganic salts . . . . . .3*12 



This may be compared with the muscle of a mollusc (Pecten) : 



Water . 



Solids . 



Proteids . 



Glycogen . 



Glycocine 



Ethereal extractives . 



Inorganic salts . 



1 CentralU.f. d. med. Wissensch., Berlin, 1869. Bd. vii. S. 1. 



2 Ewald, Ztschr.f. Biol., Mtinchen, Bd. xxvi. 8. 1. 



79-60 to 80-25 percent. 

 20-40 19-75 

 15-68 15-04 



1-98 



0-39 



0-24 



1-22 



2-43 

 0-71 

 0-33 

 1-26 



Schlossberger, " Chem. der Gewebe," Leipzig and Heidelberg, ]856, S. 169; Gornp 

 Besanez, " Lehrbuch," 1878, S. 676; Hoppe-Seyler, "Physiol. Chem.," S. 636. 

 4 Chitteuden, Ann. d. Chem., Leipzig, Bd. clxxviii. S. 266. 



