1895.] On the Nature of Muscular Contraction. 413 



stimulus is too small to be taken into consideration. The early 

 opinion that the power required for contraction was imparted to the 

 muscle through the medium of motor nerves, was refuted by experi- 

 ments, such as, e.g., those on the persistence of contractility after 

 degeneration of the motor nerves, and on the effects of direct artificial 

 stimulation of the muscles ; and it had even been refuted long ere 

 the law of conservation of energy had thrown its light on the mutual 

 connexion between the phenomena of the living organs. 



This law teaches that all the actual energy which appears in the 

 muscle in consequence of stimulation, must originate in an equivalent 

 quantity of some other form of energy. 



Now this form of energy is, in fact, given in the muscular substance 

 liable to physiological combustion. The quantity of the latter is not 

 only theoretically sufficient to produce that actual energy, but it has 

 even been proved experimentally that during contraction the 

 material gives rise to combinations, such as carbonic acid, in the 

 development of which potential chemical energy must have passed 

 into other forms of energy. So far as the phenomena have been 

 examined quantitatively, they confirm the conclusion that all muscular 

 force must be deri ved from chemical energy. 



Hence there is no difference about all these points. But with this 

 result we have as yet gained only a basis for the proper solution. As 

 soon as you inquire in what way, by what transformations, does the 

 mechanical force of contraction arise from chemical energy, diffi- 

 culties and differences of opinion begin to present themselves. 



A great many physiologists hold, with Pfliiger, Fick, and Chauveau r 

 that muscnlar force is a direct manifestation of chemical attraction ; 

 others, e.g., Solvay, think that it is produced through the medium of 

 electricity; others again, following J. E/. Mayer, believe that the muscle 

 is a thermodynamic machine, not unlike our caloric or steam engines. 



The Chemiodynamic Hypothesis. The first hypothesis, according to 

 which contraction of muscle is a direct manifestation of chemical 

 attraction we may call it the chemiodynamic hypothesis has to 

 assume that the molecules, on the chemical combination of which this 

 contraction is based, are regularly arranged within the contractile 

 substance in such a way that they necessarily approach each other, 

 during that combination, in the direction of the axis of the muscular 

 fibres. 



I think that this hypothesis of the identity of chemical attraction 

 and muscular force meets with a fundamental difficulty in the fact 

 that, in a single contraction, only a relatively infinitesimal part of the 

 muscular substance is chemically active. 70 to 80 per cent, of the 

 muscle (and even more) consists of imbibed water, the rest contains 

 substances (albumin, salts, &c.) which, for the greater part, so far as- 

 can be proved, are not chemically concerned in the contraction. 



