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Nachdruck verboten. 



A constant Bursa in relation with the Bundle of His; 

 with Studies of the Auricular Connections of the Bundle. 



By E. J. CuRRAN, M. D., 

 Assistant in Anatomy, Medical School of Harvard University. 



With 4 Figures. 

 In view of the fact that it has been suggested by Tawara that 

 the auriculo-ventricular bundle of His is a conducting and not a con- 

 tracting system, it occurred to me that there might be some mecha- 

 nism or provision to lessen the friction with the surrounding muscle 

 which must, of necessity, take place either if the auriculo-ventricular 

 bundle does or does not contract. For it must be admitted that if 

 the auriculo-ventricular bundle contracts as it delivers its impulse to 

 the ventricle, it must do so at a difi'erent time from the contraction of 

 the surrounding muscle; and if it does not contract, there must be some 

 provision to a£ford it protection from the violent impact of the systole 

 of the ventricle. Keith was impressed with the distinct fibrous sheath 

 which surrounds the bundle, isolating it from the ordinary cardiac 

 muscle and following the branches to their terminal ramifications. It 

 was about this sheath that I looked for some protecting mechanism. 

 On examining it I found that it consists of two layers, more or less 

 distinct, — one around the muscle itself and the other on the wall 

 of the canal in which it lies. These sheaths are easily separated, as 

 the space between is usually crossed by fine trabeculae well moist- 

 ened with lubricating fluid; but in some parts there are not any 

 trabeculae, — only a space with the lubricating fluid. This is espe- 

 cially the case when the chordae from the valves are inserted along 

 the main bundle, or when the bundle at its beginning disappears behind 

 a nodule of muscle to get to the left side, as in Fig. 1. The lubricating 

 fluid is of greater consistency than ordinary lymph and is somewhat 

 tenacious in character. In the fresh heart it gives the muscle a pecu- 

 liar sheen and causes it to slip easily from under a blunt instrument 

 such as the point of a pencil. This fluid is to be found throughout 

 the branches as far as they can be dissected, and it is one of the 



