A text-book of physiological chemistry : for students of medicine and physicians / by Charles E. Simon.

  • Charles Edmund Simon
Date:
1904
Catalogue details

Licence: Public Domain Mark

Credit: A text-book of physiological chemistry : for students of medicine and physicians / by Charles E. Simon. Source: Wellcome Collection.

Provider: This material has been provided by the Augustus C. Long Health Sciences Library at Columbia University and Columbia University Libraries/Information Services, through the Medical Heritage Library. The original may be consulted at the the Augustus C. Long Health Sciences Library at Columbia University and Columbia University.

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    with acids or alkalies; and here, as there, a precipitation results only if very dilute acids are used. In an excess the precipitate rapidly dissolves. On heating solutions of myosin to 35° C. the substance is gradually coagulated, while this occurs at once at a tem- perature of 50° C. In its insoluble form myosin is termed myosin-fihrin, which, like the insoluble myogen-fibrin, belongs to the class of the coagulated albumins. Of special interest, further, is the fact that on evaporating a few drops of a solution of myosin in soda solution on a slide, at a low temperature, a jelly-like material is obtained, which on polariscopic examination is seen to be doubly refracting. In this respect it behaves exactly as the anisotropic material which is found in the dark bands of the voluntary muscle-fibres. The amount of myosin found in the muscle-tissue of the rabbit is much less than that of myogen, and, according to v. Fiirth, corre- sponds to only 20 per cent, of the total amount of solu])le albumins. Significance of the Common Muscle-albumins.—Of the part which the common muscle-albumins take in the function of the cell little is known that is definite. From the researches of some ob- servers, it appears that the nitrogenous components of the albumins, at least, do not furnish the energy which is here required. Petten- kofer and Voit have thus shown that an increase in the amount of muscular work does not lead to an increased elimination of nitrogen or to an increase which is insignificant. This view is now gener- ally held; but it must be admitted that evidence is not lacking which suggests that an increased albuminous destruction may occur nevertheless when the amount of work is increased. It has been shown, as a matter of fact, that the total elimination of sulphur, which usually follows that of the nitrogen quite closely, is increased by muscular exercise and diminished thereafter. But while we may admit that the nitrogenous components of albumin may furnish a certain fraction of the energy which is recjuired in muscular work, this is, after all, but slight, and there is abundant evidence to show that by far the greater amount of energy must be referable to the decomposition of non-nitrogenous material. The question, of course, suggests itself. Do the soluble albumins of the muscle-plasma represent the contractile element of the muscle-tissue? but to this question no answer can as yet be given. We might imagine that in some manner a transformation of the soluble albumins into the fibrin form occurs, and vk-e versa ; but of this we have no evidence in the living tissue. On the other hand, it is supposed that rigor mortis, as well as the rigor which results from exposure of muscle-tissue to a temperature of 47° C, is owing to such a change, and it is possible that in either event both myosin and myogen pass over into tlie coagulated state. Folin in a recent j.aper, however, has again thrown doubt on the correctness of the coagulation theory in the explanation of rigor mortis, and has
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