74 PHYSIOLOGY OF Mrsri.Ks AND NKKVES. 



muscle. '1'ln' methods usually employed in chemistry 

 tor the separation and isolation of different substances 

 arc of no avail in this case, since they essentially alter 

 the nature of the muscle. We must, therefore, be sati 

 tied to assume as certain only that various albuminous 

 liodi.-s occur in the muscle, one of which, called myosin, 

 appears to lie peculiar to muscle, and of which others 

 are the inm-nitrogenous bodies glycogen ;m d inosit. 

 together with a certain amount of fat and a number <! 

 salts. It a])pears somewhat doubtful whether lactic 

 aciil, which is always present in the muscle, if but in 

 small (plant it ics, is to be regarded as a normal c<m- 

 .-I it uent of muscle substance, or if it is nut rather a 

 product of decomposition. The same may be said of 

 the gaseous carbonic acid which, like the lactic acid, is 

 probably only formed during the activity of the muscle, 

 and also of the nitrogenous bodieSj such as creatin, which 

 an- present in small quantities in muscle, and which 

 must probably also be regarded only as the product.- of 

 the dissolution of the albuminous bodies. 



2. The only conclusion to be drawn from tin's frag- 

 mentary information is that part of t he muscle-substance 

 unites during the activity of the muscle with oxygen, 

 forming, part ly carbonic acid, part ly less highly oxidised 

 products. That warmth is generated during these pm- 

 368868 of oxidation, as we have above stated, is not sur- 

 prising. To show this general ion of warmth, 1 1 elm holt/ 

 employed the thermo-electric method. An electric cur- 

 rent rises in a circle composed of t w<> ditVercnt metals, e.g. 

 copper and iron, a> SOMH as both points ,.f contact the 

 points \\here the metals meet or are soldered together 



acquire mieipial temperatures. The strength of this 

 current is proportionate to t he difference in temperature, 



