286 ANNUAL OF SCIENTIFIC DISCOVERT. 



showed, by an analysis of the various conditions under which 

 muscle existed, that no theory met the case so well as that of Du 

 Bois Raymond, in which the molecules of muscle were regarded 

 as centres of electro-motor action, arranged iu a dipolar series, — 

 in a word, one fluid, two forces or poles, — the repulsive polar 

 attitude maintained by the blood, and the attractive inducible by 

 nex-ve and external stimuli. 



THEORY OF MUSCULAR ACTION. 



Professor Ilcidenhain, of Breslau, has recently published a little 

 work on " The Production of Heat, etc., during IVIuscular Action," 

 an account of which may perhaps prove not uninteresting to our 

 feadcrs, since it bears closely on the application to physiology of 

 the doctrine of the conservation of force. A few words of intro- 

 duction, however, will be needed. 



A piece of dead flesh represents, by virtue of its chemical ele- 

 ments, a certain amount of "latent energy," whicli, in the natural 

 process of decay, is gradually set free as "actual" force in the 

 form of heat. The living muscle, in like manner, also represents 

 a certain amount of "latent" energy. During life, a metamor- 

 phosis (oxidation) of the muscular tissue is continually going on, 

 and, consequently, a quantity of "latent" energy is continually 

 becoming " actual." As long as the muscle is inactive, is at rest, 

 does not contract, the forms assumed by the liberated energy are, 

 as far as we know, those of electricity and heat. In every living 

 muscle there are "muscle-currents," and there is a certain amount 

 of heat given out. But when the muscle enters into a state of 

 activit}', when it contracts, another element is introduced, viz., 

 the mechanical work cftectcd by the shortening of the fibres. la 

 evei-y muscular contraction there are, therefore, four things to be 

 considered, — the chemical action, and the production of electric- 

 ity, of heat, and of mechanical work. Any comprehensive theory 

 of muscular action must be able to show how these are related to 

 each other. 



Is the chemical action natural to the muscle increased, or not, 

 during contraction ? 



If so, what becomes of the surplus of "actual " energy thus lib- 

 erated ? Does it all go over into mechanical w.ork, or partly into 

 heat and electricity ? 



If not, is there any evidence of the direct conversion, during the 

 act of contraction, of heat or of electricity, or of Ijoth, into mechan- 

 ical work, or of the diversion to the same end of some part of the 

 force ai'ising from chemical action, at the expense of some amount 

 of heat or electricity ? 



That, during contraction, there is really an inci'ease of chemical 

 action, has been generally admitted since the well-known experi- 

 ments of Helmholtz. Some, indeed, have sjioken as if they thought 

 that chemical action occurred during contraction only ; clearly an 

 erroneous conception. Voit has adopted what may fairly be called 

 an error of the opposite kind, in concluding that there is no in- 

 crease of chemical action during contraction, because no notable 



