60 RUSKIN M. LHAMON 



muscle along both the right and the left branches. At times the 

 needle was pointed downward, at others, upward. In order to 

 reach the point just under the cartilage in the ox heart where Cur- 

 ran described a bursa a centimeter in diameter, the needle was 

 inserted from high up on the left side of the septum under the 

 right cusp of the aortic valve, and directed downward and to the 

 right a distance of 8 to 10 mm., this procedure being employed 

 as a result of examination of dissected specimens. The amount of 

 pressure used in making the injections was not gauged, but it 

 was very slight, firm pressure never seeming necessary. 



The results of the first injections were good pictures of extrava- 

 sation, and subsequent dissections showed this to be the case. No 

 confining limits could be made out, for the injection material 

 extended as readily into the connective tissues between the car- 

 diac muscle fibers and out under the endocardium as into the 

 tissues immediately around the bundle. This extravasation was 

 found in all regions, whether along the course of the main bundle 

 under the cartilaginous septum, or along the larger or the smaller 

 branches of the system. Hence, unless the walls of a preformed 

 space had been ruptured by pressure, which was unlikely, we 

 must conclude that a bursa, if it exists, must extend out under the 

 endocardium and in between the cardiac musculature. Micro- 

 scopic examination of stained sections also showed the diffuse 

 character of the injection mass typical of extravasation. In the 

 case of beef heart no. 12, however, a different result was appar- 

 ently obtained. In this specimen, the attempt had been made to 

 inject the 'main bursa,' but accidentally the sheath of the bundle 

 had been pierced and the injection solution delivered within 

 it. On dissecting the main bundle from the ' Knoten' to the divi- 

 sion into the septal branches, it was seen that, the injection mass 

 was confined entirely within the sheath except at the point of 

 puncture, where some fluid had extravasated. This result sug- 

 gested the idea that it might be possible constantly to inject -the 

 sheath, and by using air in the syringe it was also found that the 

 sheath could be inflated. If, for example, air was injected from 

 the right side into the sheath of the right branch at the base of 

 the moderator band or trabecula supraventricularis, it ran up 



