THE SHEATH OF THE BUNDLE OF HIS 



65 



securing serial sections of pieces of myocardium containing parts 

 of the injected system, to trace on the one hand, the sheath with 

 the enclosed injection mass as far upward in the region of the 

 'Knoten' as the connective tissue of the auricular muscle, and on 

 the other as far into the ventricular wall as the point of termina- 

 tion of the Purkinje fibers, where the sheath becomes the perimy- 

 sium. 





* 



Fig. 3 Section showing two Purkinje fasciculi under the endocardium. A, 

 endocardium; B, injection mass within connective tissue sheath; C, Purkinje 

 fasciculus; D, connective tissues; E, cardiac muscle. X 275. 



For this microscopical work, pieces of tissue including parts of 

 the injected system were taken from the different regions, i.e., 

 from the region of the 'Knoten,' from that of the main bundle, 

 of the main branches, from the sub-endocardial anastomosis, and 

 from the terminations within the myocardium. Paraffin and 

 celloidin were employed for embedding and the sections were 

 stained with haematoxylin-eosin and van Gieson. Where the 

 fasciculus had appeared as a definite strand in the gross, the micro- 



THE AMERICAN JOURNAL OF ANATOMY, VOL. 13, NO. 1 



