228 FRANKLIN P. MALL 



young children as is pictured by Henle.^*^ I mention this as a 

 variation in the human heart, but it is certainly constant in the 

 pig's heart and caused MacCallum much difficulty in studying the 

 heart musculature. It may be that more careful examination of 

 this sheet will show that it is present on all hearts, for our present 

 method of cleaning off the epicardium might easily destroy it. 



The longitudinal bundle of Wolff lying in the posterior longitu- 

 dinal sulcus is certainly present in most young hearts and it does 

 not interfere materially with the study of the outer spiral muscle 

 bundles for it lies upon them. However, Weber observed that 

 although superifical bundles entered the septum both through the 

 anterior and the posterior longitudinal sulci, the penetrating fibers 

 were much more marked along the former than the latter. It is 

 quite easy to strip off the superficial bundles over the posterior 

 sulcus but not over the anterior, for here the sperficial bundles 

 enter the septum while behind they pass over it. This arrange- 

 ment was encountered by MacCallum in dissecting the macer- 

 ated heart of the foetal pig when he attempted to strip off the 

 superficial bundles with a blunt probe. He then found that it was 

 easy to lift off the superficial layer of muscle bundles over the back 

 of the heart but not over the front. These bundles having been 

 cut, he further found that the deeper fibers all entered the septum 

 which when broken open permitted him to unroll the musculature 

 of the left ventricle as a scroll. Through MacCallum's method of 

 dissection, which Bourgery^^ had almost invented, it is possible 

 to unravel the musculature of both ventricles in a satisfactory 

 manner, that is, the same result is obtained in all specimens.*" 



The chief bundles of the superficial fibers all arise from the 

 tendinous rings and membranes at the base of the heart, especi- 

 ally those around the aorta, as may be seen in fig. 1 . After the 

 superficial layers have been removed it is seen that the deeper 

 bundles stream towards the aorta more markedly than the super- 



ssHenle, I.e., fig. 39, B.* 



3» Bourgery, I.e., Tome 4, PL 10 b, fig. 5. 



''° Searle, Todd's Cyclopaedia of Anatomy, vol. 2, describes a similar unrolling 

 and gives excellent illustrations of specimens made in this way in his figs. 278 to 

 282. The chief circular band he calls the rope, for when unrolled it appears like 

 a twisted rope. 



