THE SHEATH OF THE BUNDLE OF HIS 59 



showed that the attachment of the sheath to the individual 

 fasciculi was relatively loose, and whether the latter were regular 

 or irregular, the sheath was usually closely applied to them, 

 although a slight separation was seen in some cases. In the main 

 mass of the bundle, small blood vessels, nerve bundles and some 

 fat were noticed. 



Repeated attempts to demonstrate the presence of a fluid 

 as found by Curran, were made by pressing on the superficial 

 parts of the bundle. For this purpose, hearts were chosen where 

 the main branches of the bundle were superficial enough to form 

 a plainly visible and palpable strand under the endocardium. 

 Since the right branch of the bundle is more cylindrical in form 

 and lies upon the convex side of the septum, it seemed better 

 adapted for this purpose. If a bursa containing fluid exists, it 

 should be found most easily along this part of the bundle. How- 

 ever, when pressure was made at distant points and the fingers 

 were made to approach each other, no bulging or pouching of the 

 endocardium from fluid pressure underneath occurred. What 

 happened was a gathering of the endocardium and the tissues 

 superficial to the bundle into a number of ridges or undulations, 

 running transversely to the long axis of the bundle. These 

 results certainly speak against the existence of fluid in a bursal 

 space and can have resulted only from the tissues being bound 

 down tightly to the underlying structures. Attempts to with- 

 draw fluid by means of a very fine capillary pipette were also 

 unsuccessful. 



The injection of various fluids into the tissues directly beneath 

 the endocardium surrounding the bundle and its branches, was 

 also used as a means of demonstrating the presence or the absence 

 of a bursa. For this purpose sixty hearts were used. Twenty- 

 nine of these were beef hearts, twenty-four sheep, six calf and one 

 from a six weeks lamb. An ordinary hypodermic syringe with a 

 relatively fine needle was used for these injections. Watery 

 suspensions of India ink, of finely precipitated Prussian-blue, 

 of Prussian-blue gelatine, and at times air, were used as injection 

 media. These were injected into the tissues between the bundle 

 and the endocardium, and between the bundle and the heart 



