64 



RUSKIN M. LHAMON 



naturally limited because of the hardening and loss of elasticity 

 of the tissues. 



That the sheath does not simulate a bursa in containing fluid 

 was well shown by injecting a fasciculus from two points, when the 

 fluids would run together perfectly without hindrance from any 

 other contained fluid. Attempts to demonstrate a lining by 

 means of a silver stain were also unsuccessful nor was it possible 

 to demonstrate microscopically the existence of definitely ar- 

 ranged nucleii which the connective tissue cells of the inner layer 

 of a bursa should show. 



Fig. 2 Ox heart; cross-section; diagram of left ventricular wall, acual size, 

 showing depths within myocardium at which the injected branches of the sino- 

 ventricular system could be traced with the naked eye. 



Tawara, who traced the Purkinje fasciculi and their sheaths 

 through the myocardium to their terminations or transitions into 

 heart muscle and perimysium respectively, states that the sheaths 

 everywhere form a closed system and isolate completely the fas- 

 ciculi from the heart muscle. From an examination of my speci- 

 mens these statements are wholly confirmed, for even with the 

 naked eye, it was possible to find injection masses in some in- 

 stances as far as fifteen millimeters in the myocardium. Fig. 2 

 is a diagram of part of the left ventricular wall of beef heart no. 

 26, and illustrates this fact. Furthermore, it was possible, by 



