588 MUSCLES. 



tained about 7 p. m. Nad, besides small amounts of CaCk (0.2 p. m.), 

 KC1 (0.1 p. m.), and NaHCO 3 (0.1 p. m.). 



The gases of the muscles consist of large quantities of carbon dioxide 

 besides traces of nitrogen. 



In regard to the permeability of the muscles for various bodies there 

 are the complete investigations of OvERTON. 1 The different sheaths of 

 the muscles, the sarcolemma and perimysium internum, offer no very 

 great resistance to the diffusion of the most soluble crystalloid com- 

 pounds, while the muscle-fibers, on the contrary (exclusive of the sar- 

 colemma), are almost if not entirely impervious to most inorganic com- 

 pounds and to many organic compounds. The muscle-fibers themselves 

 are actually semipermeable structures which are permeable to water 

 but not to the molecules or ions of sodium chloride and of potassium phos- 

 phate. The muscle-fibers, as well as the various sheaths, are impermeable 

 to colloids. 



* The behavior of the numerous bodies investigated cannot be discussed 

 in this work. The general rule is as follows: All compounds which, 

 besides having a marked solubility in water, are readily soluble in ethyl 

 ether, in the higher alcohols, in olive-oil and in similar organic solvents, 

 or are not much less soluble in the last-mentioned solvents than in water, 

 pass through the living muscle-fibers with great ease. The greater the 

 difference between the solubility of a compound in water and in the other 

 solvents mentioned, the slower does the passage into the muscle-fibers 

 take place. The permeability changes essentially on the death of the 

 muscle. 



The living muscle-fibers are readily permeable to oxygen, carbon 

 dioxide, and ammonia, while the hexoses and disaccharides do not readily 

 pass into them. It is very remarkable that a great portion of those 

 compounds which take part in the normal metabolism of plants and 

 animals belongs to those bodies to which the muscle-fibers (and also other 

 cells) are entirely or at least nearly impermeable. On the contrary, 

 derivatives can be prepared from these bodies which pass into the cells 

 very readily, and OVERTON finds that it is not impossible that the organ- 

 ism in part makes use of a similar artifice in order to regulate the concen- 

 tration of the nutritive bodies within the protoplasm. (See Chapter I.) 



Rigor Mortis of the Muscles. If the influence of the circulating 

 oxygenated blood is removed from the muscles, as after the death of 

 the animal or by ligature of the aorta or the muscle-arteries (STENSON'S 

 test), rigor mortis sooner or later takes place. The ordinary rigor 

 appearing under these circumstances is called the spontaneous or the 



1 Pfliiger's Arch., 92. See also Hober, ibid., 106, and Hamburger, Osmotischer 

 Druck und lonenlehre. Bd. 3. 



