434 THE DYNAMICS OF CARDIAC ACTION. 



Indeed, the intimate structure of the myocardium pre- 

 cisely supplies the required structure for the equable and free 

 distribution of such an agency as the suprarenal secretion rep- 

 resents. Fluids can penetrate through the maze of cellular 

 tissue to the bare muscular fibers; the sheaths that include 

 the columns or chains of muscular bundles afford a peculiar 

 system of canalization through which the liquids can easily 

 gain access to them. These canals the lacunae of Henle 

 are the intervals between the columns of secondary bundles, or 

 their sheaths, rather, which are placed in longitudinal apposi- 

 tion. Schweigger-Seidel and Eanvier having observed that 

 interstitial injections of colored substances penetrated the 

 lymphatic vessels, the lacunae have been considered as adjuncts, 

 or extensions, of the latter. 



Renaut, 13 however, concluded that the penetration of the 

 colored fluids into the lymphatics merely demonstrated the 

 weak resistance of the endothelial coat of the latter, and the 

 spaces, or lacunas, of Henle being unprovided with endothelial 

 walls, there was no ground for the prevailing belief that they 

 represented lymphatic vessels. He found that all the lym- 

 phatic capillaries of the myocardium are located on the surface 

 of the heart underneath the pericardium. They are large and 

 bosselated and form a mesh-work which covers the whole car- 

 diac surface, and send smaller blind pouches into the muscular 

 interstices. The spaces of Henle should be considered, he 

 thinks, "not as true lymphatic cavities analogous to those ob- 

 served around the pulmonary lobules of certain animals, but 

 as mere connective-tissue spaces, which represent, in fact, 

 pathways for lymph." In a foot-note Berdal states that the 

 spaces of Henle are crossed by "vessels," and in the text the 

 following remark as to the identity of this lymph appears: 

 "The muscular fibers of the heart are thus bathed in con- 

 nective-tissue spaces in which lymph easily circulates; but 

 this lymph is not that of the lymphatic vessels or capillaries, 

 but that of loose connective-tissue spaces (Kenaut)." It is 

 needless to state that this suggests the presence of blood- 

 plasma. Still, we can only consider this deduction as tentative. 



13 Renaut: Trait6 d'Histologie pratique, p. 719; quoted by Berdal, loc. cit., 

 p. 285. 



