56 RUSKIN M. LHAMON 



Her models are, therefore, representations of the bundle and con- 

 nective tissue sheath. Curran in 1909, stated that a mucous 

 bursa, was constantly present in relation to the bundle and its 

 branches in the human, calf, beef, and sheep hearts which he 

 examined. According to Curran, the so-called bursa is best 

 demonstrated by gross dissection, but he also succeeded in dis- 

 tending it by a blow pipe, the character of which was however 

 not stated, and in many cases, saw bubbles of air in the region 

 of his ' reticulum' upon the interauricular septum, and upon the 

 sides of the interventricular septum, along the courses of the right 

 and left branches. What Curran means by 'reticulum' is not 

 quite clear, but presumably he refers to the gross structure of the 

 bundle in the region where the ' Knoten' (Tawara) is found. He 

 also stated that the bursa contains a fluid which is of greater con- 

 sistency and more tenacious than ordinary lymph. In some 

 cases, it was said to be so plentiful as to exude in the form of a 

 droplet when the bursa was punctured, in others the overlying 

 tissues could be made to puff out by making pressure on both 

 ends of the branch. The place where this bursa was said to reach 

 its greatest dimensions was just under the cartilaginous part of 

 the septum, where the impact or friction with surrounding parts 

 would presumably be greatest. From his microscopic work 

 Curran concluded that the nature of this space varies from "very 

 loose areolar tissue with fluid in the cellular spaces, which always 

 connect with each other along the line of the bundle, to distinct 

 cavities, filled or lubricated with fluid and no trabeculae crossing 

 the intervening space. In the usual form, there are one or two 

 large spaces or one continuous space with very fine trabeculae 

 crossing from the walls of the canal to the auriculo-ventricular 

 muscle." Curran, however, does not state whether these spaces 

 are lined with a special endothelium or by a membrane similar 

 to synovial membranes. 



Dogiel in 1910, sought to throw doubt upon the existence of the 

 auriculo-ventricular system as a muscular connecting link between 

 the heart chambers and stated that the origin and the termina- 

 tion of such a nerveless bundle, its relation to the nerves, to the 

 connective tissue, and to the rest of the heart muscle, are anatom- 

 ically and physiologically unknown, and according to him, no 



