MUSCLE. 261 



water at 14-15 C. and contains 18.18$ water of crystallization, cor- 

 responding to the formula Zn(C 3 H 6 03) 2 -f 3H 2 0. The zinc salt of 

 paralactic acid dissolves in 17.5 parts of water at the above temper- 

 ature and contains ordinarily 12.9$ water, corresponding to the 

 formula Zn(C 3 H 5 03) 2 -f- 2H 2 0. The calcium salt of fermentation 

 lactic acid dissolves in 9.5 parts water and contains 29.22$ 

 (=5 rnol.) water of crystallization, while the calcium paralactate 

 dissolves in 12.4 parts water and contains 24.83 or 26.21$ (=4or4| 

 mol.) water of crystallization. Both calcium salts crystallize, not 

 unlike tyrosin in spheres or tufts of very fine microscopic needles. 



Lactic acids may be detected in organs and tissues in tlie follow- 

 ing manner: After complete extraction with water the albumin is 

 removed by coagulation at boiling temperature and the addition of 

 & small quantity of sulphuric acid. The liquid is then exactly 

 neutralized while boiling with caustic baryta, and then evaporated 

 to a syrup after filtration. The residue is precipitated with absolute 

 alcohol, and the precipitate completely extracted with alcohol. 

 The alcohol is entirely distilled from the united alcoholic extracts, 

 and the neutral residue is shaken with ether to remove the fat. 

 The residue is taken up by water and phosphoric acid added, and 

 repeatedly shaken with fresh quantities of ether, which dissolve the 

 lactic acid. The ether is now distilled from the several 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 evapo- 

 rated until crystallization commences and then allowed to stand 

 over sulphuric acid. 



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

 the inter-muscular connective tissue; but the muscle-fibres them- 

 selves also contain fat. The amount of fat in the real muscle sub- 

 stance is always small, usually amounting to about 10 p. m. or 

 somewhat more. A considerable amount of fat in the muscle-fibres 

 is only found in fatty degeneration. Lecithin is also habitually 

 found in the muscles. 



The Mineral Bodies of the Muscles. "We have no complete 

 analyses of the mineral substances of the pure, blood-free muscle 

 substance. 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 constituents are potassium and phos- 



