480 THE RESPIRATORY MECHANISM. 



enter into the functional mechanism of other organs; it seems 

 to us to warrant the deduction that the pulmonary lobules 

 do not differ from the latter either in the manner in which 

 their functional activity is governed or in the processes through 

 which they are supplied with mechanical energy. 



But we must lay special stress upon the important func- 

 tional connection that exists between the pulmonary lobule 

 and the right heart. Indeed, we must not lose sight of the 

 fact that venous blood is distributed to the lobules. This 

 venous blood, brought to them by the pulmonary capillaries, 

 only contains adrenal secretion, obviously incapable of insuring 

 functional metabolism of the lobular epithelium. But how, 

 then, is this secured? The answer is not difficult to find after 

 all we have said regarding the processes that obtain in the 

 right myocardium. Indeed, we have in the pulmonary alveolar 

 walls precisely the conditions that prevail in the cardiac wall: 

 i.e., the granules ft and the oxidizing substance of arterial blood. 

 While the granules ft also emanate from the liver, and repre- 

 sent the bulk of those unused in the right heart, the oxidizing 

 substance, instead of being supplied by the coronary, as in the 

 heart, originates from the vessels to which we have already 

 referred: i.e., the bronchial terminal arterioles. This anastomo- 

 sis between the bronchial and pulmonary systems is a generally 

 recognized fact; but its vast importance does not seem to us 

 to have ever been suspected. 



May the secretion of the adrenals also produce contractile 

 effects upon the lobular walls? The wealth of elastic fibers 

 in the latter suggests that such might be the case, the purpose 

 being to maintain their tone and insure resiliency after unusual 

 dilation. As we will see in the twelfth chapter, the adrenal 

 secretion is active in various ways in this location. 



Collectively considered, however, the various elements of 

 the process may be said to distinctly show that respiration, as 

 regards its chemical phenomena, starts in the adrenals and 

 ends in the pulmonary lobules, with the inferior vena cava, the 

 right heart, and the pulmonary artery as mechanical inter- 

 mediaries, and thus constitutes an autonomous system. 



The following deductions appear to us to embody the 

 principal facts developed in the present chapter as regards the 



