264 PHYSIOLOGICAL CHEMISTRY. 



ing strongly acid and the myosin-clot dissolving in the acid, and 

 partly, and in all probability mainly, upon a putrefaction. 



Exchange of Material in the Inactive and Active Muscles. It is 

 admitted by a number of prominent investigators, PFLUGER and 

 COLASANTI, ZUNTZ and ROHRIG, and others, that the exchange of 

 material in the muscles is regulated by the nervous system. 

 When at rest, when there is no mechanical exertion, we have a 

 condition which ZUNTZ and ROHRIG have designated "chemical 

 tonus" This tonus seems to be a reflex tonus, for it may be re- 

 duced by discontinuing the connection between the muscles and 

 the central organ of the nervous system by cutting through the 

 spinal marrow or the muscle -nerves, or by paralyzing the same by 

 means of curara poison. It may also be reduced or checked by 

 adjusting the temperature between the skin and the surrounding 

 medium; or it maybe increased by the reverse, by irritating the 

 nerves of the skin by cooling. The possibility of reducing the 

 chemical tonus of the muscles by any of the above-mentioned 

 means, but especially by the action of curara, offers an important 

 means of deciding the extent and kind of chemical processes going 

 on in the muscles when at rest. In comparative chemical investi- 

 gation of the processes in the active and in the inactive muscles 

 several ways of procedure have been adopted. The removed 

 homologous, active and inactive muscles have been compared, also 

 the arterial and venous muscle-blood in rest and in activity, and 

 lastly the total exchange of material, the receipts and expenditures 

 of the organism, have been investigated under these two conditions. 



By investigations according to these several methods, it has 

 been found that the active muscle takes up oxygen from the blood 

 and returns to it carbon dioxide, and also that the quantity of 

 oxygen taken up is greater than the oxygen contained in the car- 

 bon dioxide eliminated at the same time. The muscle, therefore, 

 holds in some form of combination a part of the oxygen taken up 

 while at rest. During activity the exchange of material in the 

 muscle, and therewith the exchange of gas, is increased. The 

 animal organism takes up considerably more oxygen in activity 

 than when at rest, and eliminates also considerably more carbon 

 dioxide (REGNAULT and REISET and others). The quantity of 

 oxygen which leaves the body as carbon dioxide is, during activity, 



