454 



THE RESPIRATORY MECHANISM. 



substance, contraction of the muscle-cells is induced as it is else- 

 where in the organism. 



14- The adrenal secretion and the granules fi, which do not 

 enter the Thebesian channels, are carried to the lungs with the 

 venous blood of the right ventricle. 



15. The mechanical energy of the left heart is supplied (1) 

 by the oxidizing substance of the arterial blood, which penetrates 

 its muscular structures and its cavities by the coronaries and the 

 pulmonary veins, and (2) by an additional supply of myosinogen- 

 building granules (3 , and perhaps of adrenal secretion, which find 

 their way to its myocardium through the Thebesian channels that 

 connect it with the right heart. 



16. The manner in which the contractile process is carried 

 on in the walls of the left heart is similar to that which prevails in 

 the right heart. 



THE ADRENAL AND VAGAL SYSTEMS IN THEIR RELATIONS 

 TO RESPIRATORY FUNCTIONS. 



The role of the suprarenal secretion in respiration, and 

 particularly the process through which oxygen is taken up by 

 the blood, was reviewed in the second chapter. We believe that 

 the succeeding chapters, by affirming the importance of the 

 oxidizing substance in every part of the organism, have but 

 confirmed the conclusions reached concerning the process in 

 question. The fact that the interchange of oxygen and car- 

 bonic acid between the alveolar air and the blood by mere 

 diffusion was inadequate to account for the experimental results 

 of various investigators, particularly Bohr and Haldane and 

 Smith, has therefore been correspondingly emphasized. We 

 must also refer to the fact, however, that the belief of Ludwig, 

 Bohr, and others, that the alveolar tissues might be the seat 

 of functions capable of fulfilling the missing requirements 

 of the process, has not been sustained by our inquiry. On the 

 other hand, the role of the adrenal secretion in the lungs as 

 we have defined it seems to have supplied these requirements, 

 notwithstanding the severe tests to which it has been submitted 

 in previous chapters. 



We have seen that the adrenal secretion, conveyed to the 

 lungs with the venous blood, is not only able to take up oxy- 



