244 FRANKLIN P. MALL 



The deep bulbo-spiral band having been removed the continua- 

 tion of the superficial band below is revealed. This now encircles 

 the heart and ends below and behind the aorta in the aortic 

 septum as shown in figs. 8, 10, 12, X. Fig. 11 shows the deep bulbo- 

 spiral band drawn upon the outline of fig. 10.'^" The older 

 authors recognized this cylinder of circular fibers around which the 

 superficial and deep fibers are wrapped to form the vortex. This 

 arrangement may be seen by superposing figs. 10 and 11 as well 

 as in fig. 12. Krehl also recognized that the deep bulbo-spiral band 

 was intimatel}^ connected with fibers from the apex, for he states 

 expressly that not only fibers from the outer and inner layers but 

 also numerous fibers from the circular layer pass to the apex of 

 the heart. His description of the circular bands is by no means 

 consistent for he describes it as a cylinder, as a cylinder with fibers 

 going to the apex, and pictures it as a basket entirely closed below. 

 These variations are due entirely to the thickness he gives to this 

 layer. 



Coming back now to the superficial bulbo-spiral band, it is seen 

 that it enters the apex and passes below the deep bulbo-spiral 

 band, blends with it to encircle the left ventricle and with a general 

 upward tendency ends in the septum aorticum below and behind 

 the aorta. That is these fibers make nearly a double circle around 

 the heart to form the figure 8 of Gerdy and Ludwig. The lower 

 loop of the 8 encircles the apex and the upper loop lies within the 

 deep bulbo-spiral band. It is also clear that my figure 8 is not 

 closed above, just as Gerdy described it, and that its two free 

 ends are attached to the septum aorticum on the two sides of the 

 aorta. 



In my description I have included with the deep bulbo-spiral 

 band those circular fibers which pass through the septum as a sin- 

 gle bundle, fig. 12, BS', between the superficial bulbo-spiral bundle 

 BS, the sino-spiral bundle, SS, and the longitudinal bundle of the 

 right ventricle, LRV. Two views of the deep bulbo-spiral band are 

 shown in figs. 9 and 11. It is noticed at once that the course of the 



•' This cylinder of fibers was well known to Winslow, Wolff and Weber (Weber, 

 I.e., pp. 151, 152) and had recently been described anew by Krehl. 



