234 THE ADRENAL SYSTEM AND VASOMOTOR FUNCTIONS. 



proceed without clearing this question, we will first ascertain 

 whether the prevailing views as to the physiology of the cir- 

 culation in the muscular system may not, in the light of our 

 own conceptions, be subject to change. 



THE OXIDIZING SUBSTANCE AND MYOSINOGEN. In the 

 production of muscular contraction a nerve-impulse is of 

 course transmitted to the muscular elements; but how are this 

 impulse and the resulting contraction related to the functions 

 of the blood itself? This question is suggested by the role 

 assigned in the foregoing pages to the oxidizing substance. 



Stewart 1 refers to the thermal phenomena of muscular 

 contraction as follows: "When a muscle contracts, its tem- 

 perature rises; the production of heat in it is increased. This 

 is most distinct when the muscle is tetanized, but has also been 

 proved for single contractions. The change of temperature 

 can be detected by a delicate mercury- or air- thermometer; 

 and., indeed, a thermometer thrust among the thigh-muscles 

 of a dog may rise as much as 1 to 2 C. when the muscles 

 are thrown into tetanus/' That tetanus is a phenomenon of 

 hypcroxidation through suprarenal overactivity we have re- 

 peatedly seen when studying the action of drugs. This affords 

 a first clue: If the plasma contains an oxidizing substance, the 

 chemical changes in muscular tissue during contraction i.e., 

 absorption of oxygen, increased production of carbon dioxide, 

 change of reaction from neutral or alkaline to acid, and finally 

 the formation of sarcolactic acid clearly suggest that the 

 contractile process and the mechanical energy utilized may 

 be due to an increased supply of oxygen through the agency 

 of the oxidizing substance. Indeed, Kronecker has shown 

 that "the injection of arterial blood or even of an oxidizing 

 agent like potassium permanganate into the vessels of an ex- 

 hausted muscle also causes restoration." If an agency so 

 remote in composition from the normal organic fluids can 

 i <More merely through its oxidizing power an exhausted mus- 

 cle, so eminently physiological a fluid as the blood-plasma, 

 with oxy-rn in loose combination, must surely p<> 



active proi.-crii.-s. Indeed, the link seems to 



Stewart: .M;un:;il of Physiolojry," p. 508. 



