10 On the Composition of the Muscles in the Animal Series. 



the substance which gives acidity to the muscles of all the Yerte- 

 brata, we thought it of interest to isolate this principle and to 

 analyze it. The result of our researches in this direction is, that 

 if in some cases, the acidity of the muscles is due to lactic acid, 

 that which makes the muscular fibre strongly acid is ordinarily a 

 phosphate of potash, having, according to our analysis, the for- 

 mula, KO, 2HO, PO 5 . We obtained this salt in a crystallized 

 condition by treating the muscles with weak alcohol and evapo- 

 rating the liquor to a syrupy consistence. 



While determining the proportion of this salt in the muscles 

 of different animals, we observed evidence of some connection 

 with the formation of the osseous system ; that is, we always 

 found it largely in animals in which the bones are very much 

 developed, and very slightly in the Articulata and Mollusca. 

 The part which this salt takes in the formation of bones is now 

 clear ; for we have directly ascertained that in reacting on car- 

 bonate of lime, the phosphate of potash from the muscles, forms 

 the basic phosphate of lime, which is so considerable a part 

 of the bony substance. This phosphate of potash is not, per- 

 haps, without effect in the production of a phosphuretted fatty 

 matter that exists in the muscles, which will be mentioned far- 

 ther on ; we think, however, that under these circumstances, it 

 deserves the attention of physiologists. The muscles of the ver- 

 tebrated animals are impregnated with a considerable quantity of 

 fatty bodies made up of varying proportions of olein, margarin, 

 and stearin. Besides these neutral fatty bodies, another is always 

 found, which differs from the substances properly called fat by a 

 number of peculiarities, and presents some analogy to the cere- 

 bral fat. We have made a tolerably complete examination of 

 this interesting substance. It was extracted easily by treating 

 the muscles with weak alcohol, which dissolves it without alter- 

 ing the other fatty bodies. This liquid, when evaporated, gives 

 a viscous amber-colored substance, which partly dissolves in 

 water ; treated .with sulphuric acid, it decomposes like a soap, 

 giving sulphate of soda and an acid heavier than water. This 

 acid contains both azote and phosphorus ; analyzed, it afforded 

 exactly the composition which one of us obtained from the cere- 

 bral fat, called oleophosphoric acid. 



The phosphuretted fat which exists in the muscles, is therefore 

 identical with that which is found so plentifully in the brain, and 

 is produced, like the latter, by the combination of soda and oleo- 

 phosphoric acid. This substance can now be said to be found in 

 every part of the animal organization. We have established that 

 its proportion in the muscular tissue increases with the age of the 

 animal, and it is as various as the different species of the verte- 

 brate animals. Fishes, such as the whiting, the dab, the floun- 

 der, have only a very small proportion, while species having a 



