558 MUSCLES. 



Tlie 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 

 diagonal bundles, and phosphoric acid. Next in amount we have sodium 

 and magnesium, and lastly calcium, chlorine, and iron oxide. Sulphates 

 exist only as traces in the muscles, but are formed by the burning of the 

 proteins of the muscles, and therefore occur in abundant quantities in the 

 ash. The muscles contain such a large quantity of potassium and phos- 

 phoric acid that potassium phosphate seems to be, unquestionably, the 

 predominating salt. Chlorine is found in such insignificant quantities 

 that it is perhaps derived from a contamination with blood or lymph. 

 The quantity of magnesium is, as a rule, considerably greater than that 

 of calcium. Iron occurs only in very small amounts. SCHMEY l found 

 variations between 0.0129 p. m. (rabbits) and 0.0793 p. m. (human), 

 calculated on the fresh muscle substance. The heart-muscle was com- 

 paratively richer in iron, 0.06-0.109 p. m. 



URANO 2 has removed the salts of the intermediary fluid (blood, lymph) 

 from frogs' muscle by treating them with an isotonic cane-sugar solution 

 (of 6 per cent) and in this manner found that the sodium did not belong 

 to the muscle substance itself, but to the intermediary fluid, while at least 

 a small part of the chlorine is a true muscle constituent. He also cal- 

 culated from the quantity of sodium that the intermediary fluid, if it has 

 about the same composition as the muscle plasma, makes up about one- 

 sixth of the volume of the muscle. According to more recent investiga- 

 tions of URANO the possibility of a disturbance in the osmotic properties 

 of the muscle fibres by the sugar solution is not entirely excluded, and the 

 question whether the muscle fibres are free from sodium or not has there- 

 fore not been positively decided. FAHR'S 3 researches make the absence 

 of sodium in frog's muscle very probable. 



The importance of the various mineral bodies for the function of the 

 muscles has been studied by several experimenters (LOEB, LINGLE, 

 HOWELL, OVERTON, LANGENDORFF and HuECK, and others 4 ) . Further 

 proof as to the previously discussed ion action of the electroytes and the 

 antagonism of various ions has been given by many very interesting 

 investigations. These researches also indicate that each of the ions 

 Na, Ca, and K plays a certain part in the maintenance of the excitability, 



1 Macallum, Journ. of Physiol., 32; Schmey, Zeitschr. f. physiol. Chem., 39. 



2 Zeitschr. f. Biol., 50. 



3 Urano, ibid., 51; Fahr, ibid., 52. 



4 Loeb, Amer. Journ. of Physiol., 3, and Pfliiger's Arch., 80, 91; Lingle, Amer. 

 Journ. of Physiol., 4 (also references to literature); Overton, Pfliiger's Arch., 92 and 

 105; Langendorff and Hueck, ibid., 96. 



