MUSCULAR ARCHITECTURE OF THE HUMAN HEART 223 



Wolff fail, as well as those of the earlier anatomists. However, 

 it appears that Gerdy's study interpreted this portion of the heart 

 wall in a very satisfactory manner, although his work was not 

 accepted by Weber. Weber states expressly that Gerdy's work 

 was so poorly presented that it was impossible for him to sepa- 

 rate the theoretical from the observations in it. Although Weber 

 could not confirm the fleshy fibers which connect the papillary 

 muscles of the right and left ventricles they really do exist, as 

 has been shown by MacCallum and as I have also frequently 

 observed. Furthermore, Gerdy described and pictured nearly 

 correctly the strand of muscle fibers which I have called the super- 

 ficial bulbo-spiral bundle. 2° This he describes as a bundle 

 which crosses upon itself to form a figure 8 a comparison which 

 has been applied quite differently by later investigators. Subse- 

 quently the ventricle wall including the septum was carefully 

 investigated by Ludwig and than by Krehl, whose work comes 

 from Ludwig's laboratory. They constantly kept before their 

 minds the heart as a whole, and the function it has to perform 

 in contracting. 



A good account of the middle muscular layer of the left 

 ventricle is given by Krehl who describes it as a cylindrical band 

 of fibers which form loops and do not end at the atrio- ventricular 

 ring. Although this circular muscle was recognized by Weber^^ 

 it is here described anew and is known in the literature as Krehl's 

 Triebwerk. That the fibers of the Triebwerk arise also from the 

 atrio-ventricular ring my own studies show. Below a bundle 

 extends from it to the apex, as was noted by Krehl. ^2 



The cylindrical muscular band described by E. H. Weber and 

 by Krehl is nothing but the transverse fibers of the left ventricle 

 repeatedly described by anatomists during the past two cen- 

 turies. ^^ That this layer of fibers can be shelled out of the wall 



2" Although this bundle is not quite correctly given in Gerdy's fig. 12, it is easily 

 seen that he observed it in his specimens. 



^1 Weber, I.e., p. 148. AlsoRied, Todd's Cyclopaedia of Anatomy and Physiology, 

 London, 1836, vol. 2, page 592. 



22 Krehl, I.e., p. 348. 



2' These are the spiral fibers of the middle layer according to Borelli and Lower. 

 Haller, I.e., states that the transverse fibers of the middle layer go to form the 

 septum. 



