PREFACE AND SUMMARY OP CONTENTS. IX 



testinal glandular elements, etc., were all found to be so dis- 

 posed as to allow the free circulation of this oxidizing plasma, 

 the red corpuscles passing on in the larger channels. An 

 exception to this rule was found, however, in the heart-muscle: 

 Oliver and Schafer, as is well known, ascribed to the adrenal 

 secretion the power to contract muscular tissue, and particu- 

 larly cardiac muscle. We found that contraction of the heart- 

 walls was, in great part, due to this secretion, and that the 

 latter penetrated the heart-substance by way of the Thebesian 

 foramina. The coronary arteries did not lose their functional 

 importance, however; they also were found to supply the car- 

 diac muscle-fibers with oxidizing substance. 



Still, the mere presence of oxygen in organic combination 

 in cellular elements did not account, of course, for the physical 

 phenomena witnessed, and it became necessary to ascertain the 

 identity of the agencies with which the oxygen of the plasma 

 combined. In the muscular elements myosinogen proved to be 

 the primary source of residual energy. When combined with 

 the oxidizing substance of the plasma, this organic body lib- 

 erated, we ascertained, the mechanical energy required for a 

 given contraction, the nerves serving only to incite and govern 

 muscular function. The blood was also found to be supplied 

 with a body similar to myosinogen, i.e., fibrinogen, which like- 

 wise combined, but in fixed quantities, with a corresponding 

 proportion of the plasma's oxygen. The fluctuations of the 

 blood's temperature were traced to corresponding variations in 

 the quantities of fibrinogen supplied to the plasma. In the 

 nervous system the immanent source of functional energy was 

 found to be the myelin, or white substance of Schwann, its 

 active constituent being lecithin, composed mainly of hydro- 

 carbons and containing considerable phosphorus. This myelin 

 was not only found to surround the axis-cylinders of all nerves, 

 but also to line the inner surface of the dendrites of neurons 

 and to form the ground-substance of their cell-body. It thus 

 became apparent that the entire nervous system was built upon 

 the same plan: i.e., cylinders containing oxygen-laden plasma 

 surrounded by a layer of myelin, and that the reaction between 

 these two bodies served to form and liberate nervous energy. 



The overwhelming importance of the internal secretion 



