154 M. R. KING 



of silver nitrate were used — a solution (1-400) was found to be 

 satisfactory. This solution was used only when fresh hearts 

 were obtained. The injected area was exposed to strong light 

 for a few minutes until it assumed a brown color before it was 

 examined. 



The verification of Lhamon's work was found to be an easy 

 matter. The first series of 12 hearts were used for this purpose 

 and also to obtain a more practical knowledge of the technique 

 necessary for the work in hand. The repetition of Lhamon's 

 work was also facilitated by the presence of two of his injected 

 specimens in the laboratory which were often referred to. 



Within the left ventricle of a freshly-opened, uninjected beef 

 heart one can see the distribution of the bundle in many places, for 

 it appears under the endocardium as a pale, pink tracing against 

 the darker myocardium. The main branch can always be seen 

 passing down the middle of the septal wall. Having reached a 

 point about half way between the apex and the aortic orifice it 

 suddenly forks sending two or more large branches across the 

 ventricular cavity to the posterior ventricular wall. Other 

 branches remain in the septal wall and divide, unite and sub- 

 divide as they proceed towards the region of the apex. In this 

 region numerous branches cross from the septal to the posterior 

 ventricular wall which together with the above-mentioned larger 

 bridges constitute the trabeculae tendinae, i.e., false tendons 

 (pseudo-tendinous threads) as they are often called, of the left 

 ventricle. 



If a needle be properly inserted in the sheath of one of the 

 fasiculi in any of the above-mentioned places in the region of 

 the fine anastomosing fasciculi or the main branch, the surround- 

 ing system can be injected over a more or less extended terri- 

 tory. The direction in which the injection is made makes no 

 difi"erence so far as the flow of the injected fluid is concerned. 

 The needle may be pointed up or down or transversely if anasto- 

 mosing fasciculi are chosen which run in a transverse direction. 

 It was found an easy matter to insert the needle in the sheath of 

 any of the anastomosing fasciculi making up the network of 

 Purkinje fibres on the ventricular walls. 



