586 MUSCLES. 



shaken with ether to remove the fat. The residue is dissolved in water 

 and phosphoric acid is added, and the solution repeatedly shaken with fresh 

 quantities of ether, which dissolves the lactic acid. The ether is now 

 distilled from the united ethereal extracts, the residue dissolved in water, 

 and this solution carefully warmed on the water-bath to remove the last 

 traces of ether and volatile acids. A solution of zinc lactate is prepared 

 from this filtered solution by boiling with zinc carbonate, and this is 

 evaporated until crystallization commences, and is then allowed to stand 

 over sulphuric acid. An analysis of the salts is necessary in careful 

 work. In regard to methods for the detection and quantitative estima- 

 tion of lactic acid we must refer to larger hand-books. 



Fat is never absent in the muscles. Some fat is always found in the 

 intennuscular connective tissue; but the muscle-fibers themselves also 

 contain fat. The quantity of fat in the real muscle substance is always 

 small, usually amounting to about 10 p. m. or somewhat more. A con- 

 siderable quantity of fat in the muscle-fibers is found only in fatty degenera- 

 tion. A part of the muscle-fat can be readily extracted, while another 

 part can be extracted only with the greatest difficulty. This latter 

 part, it is claimed, exists finely divided in the contractile substance 

 itself and is richer in free fatty acids, standing, according to ZUNTZ and 

 BoGDANOW, 1 in close relation to the activity of the muscles because 

 it is consumed during work. Lecithin is a regular constituent of the 

 muscles, and it is quite possible that the fat which is difficult of extrac- 

 tion and which is rich in fatty acids depends in part on a decomposition 

 of the lecithin and the phosphatides. ERLANDSEN has shown that 

 phosphatides of various kinds occur in the muscles, the quantities 

 varying in different muscles. According to him the ox-heart muscle 

 is richer in phosphatides than the muscle of the thigh, and RuBow 2 

 claims that the heart of the dog is richer in phosphatides than the striated 

 muscle. ERLANDSEN found lecithin and diamino-phosphatide in the 

 heart as well as the thigh-muscle, while the monoamido-phosphatide 

 cuorin, which occurs abundantly in the heart, is found as traces in the 

 thigh-muscle. CosTANTiNO 3 has carried on investigations on the divi- 

 sion of the inorganic and organic phosphorus in striated and smooth 

 muscles. 



The Mineral Bodies of the Muscles. The ash remaining after burning 

 the muscle, which amounts to about 10-15 p. m., calculated on the moist 

 muscle, is acid in reaction. The largest constituent of the ash is potas- 

 sium, whose occurrence, according to MACALLUM,* is restricted to the dark 



1 Arch, f . (Anat. u.) Physiol., 1897. 



2 Erlandsen, Zeitschr. f. physiol. Chem., 51; Rubow, Arch. f. exp. Path. u. Pharm., 

 52. 



'Bioch. Zeitschr., 43. 

 4 Journ. of Physiol., 32. 



