234 FRANKLIN P. MALL 



left ventricle.^" It is this bundle which Ludwig '^ describes as 

 arising from the border between the septum and aorta and from 

 the free border of the papillary muscle of the right ventricle. It 

 continues forward and downward to the anterior surface of the 

 apex of the heart where it enters the septum along the anterior 

 longitudinal sulcus by the way of the vortex. Probably the best 

 description is by MacCallum, who isolated this bundle by his 

 method of dissection. It is clearly shown in fig. 3 and its distri- 

 bution over the inner wall of the right ventricle is shown in fig. 

 15. Here it is seen to blend with the sino-spiral bundle in the 

 anterior horn of the vortex and is ultimately lost in the papillary 

 muscles of the left ventricle. It therefore belongs to the interven- 

 tricular bands of Gerdy and MacCallum. 



By cutting this bundle the septum may be split completely as 

 fig. 3 shows. The conus is next separated from the aorta and its 

 tendon, to demonstrate the septum aorticum. From here super- 

 ficial fibers encircle the heart; these are indicated by the cut sur- 

 face in fig. 4, A. In fig. 3 the fibers of the horns of the vortex have 

 been separated which can easily be done with the fingers or with 

 the handle of a scalpel. Those from the anterior horn of the vortex 

 have an inward tendency, while those from the posterior horn 

 course towards the septum and come to cross the others at right 

 angles as shown in fig. 4. In separating the two horns of the 

 vortex it is found that the cavity of the left ventricle is soon reached 

 and in order to reach it most easily it is well to have a probe passed 

 into the heart to its apex where it can easily be felt from the out- 

 side. At this point the walls of the left ventricle are thinnest, in 

 proportion to the diameter of the lumen as Weber has pointed 



OUt.^2 



So far it is quite easy to unroll human hearts with constant 

 results, but when it comes to a study of the deeper layers of the 



*" This bundle is shown in Gerdy's diagram, fig. 12.- 



51 Ludwig, I.e., p. 199. 



5- Weber, I.e., p. 144, says that this thin area is not remarkable because in differ- 

 ent animals the heart thickness is in proportion to the diameter of the lumen, so as 

 the lumen varies in different portions of the heart the wall varies correspond- 

 ingly. Now we say "functional adaptation." 



