432 On the Nature of Muscular Contraction. [Mar. 14, 



inotagmata would be continually or periodically filled by others, 

 probably through the same process of organic crystallisation by which 

 during ontogenesis the doubly-refracting particles in the muscle are 

 produced and arranged. 



Against this hypothesis, however, or at least against its general 

 validity, various objections may be put forward. I will mention but 

 two of the most important of them. 



There seems to be no doubt but that the doubly-refractive 

 particles of the muscle consist of an albuminous substance, and that 

 they together make up a sensible part of the whole albumin of the 

 muscle-fibrils. In that case it would be most improbable that a 

 great increase of muscular work should not at all, or only very 

 slightly, increase the elimination of nitrogen. To account for this, we 

 should have to recur to an auxiliary hypothesis, and assume either 

 that the nitrogenous remainder of the destroyed inotagma is retained 

 within the body perhaps in the muscle for purposes of anabolism, 

 or, which is indeed most improbable, that other organs saved just as 

 much albumin as was decomposed above the normal quantity during 

 the contraction of the muscles. 



A second objection consists in the fact that after heating or tetanis- 

 ing muscles until they are rigid, the doubly-refractive power of the 

 sarcous elements will be found still very great. 



The other possibility is that the inotagmata may be preserved, and 

 consequently on cooling may return to their former state, and 

 therefore will do work by shortening as often as we choose. In this 

 case muscle would not only seem to offer, but would in fact offer a 

 most striking resemblance to a thermodynamic machine, the solid 

 particles of the framework of which are not destroyed through the 

 chemical process producing the actual energy. No more than such a 

 machine would the muscle require a perpetual renewal of its 

 framework for the continuation of its activity ; it would only want a 

 periodic supply of fresh combustible material. 



This representation, as you see, will sufficiently account for the fact, 

 which would otherwise remain surprising, that muscular work has 

 such a small influence on the elimination of nitrogen. The facts of 

 microscopic observation also agree with it. 



But a further discussion of the two possibilities would lead us too 

 far. The purpose of this lecture was not to give a complete account 

 of all the phenomena of muscular activity. I have wished chiefly 

 to draw your attention to a series of facts which I hold to be of great 

 importance for a deeper insight into the essence of muscular con- 

 tractility, in so far as they prove the existence of certain material 

 dispositions and processes (admitting of closer experimental examina- 

 tion), by means of which mechanical work may be generated in the 

 muscle by chemical energy. 



