97 



Summary. 

 The important new facts and considerations brought out in this 

 study are the following: 



1) That there is a bursa or lubricating mechanism in constant 

 relation with the auriculo-ventricular bundle, in view of which the 

 possibility of bursitis must be considered in connection with certain 

 temporary cardiac symptoms, and with conditions met with in acute 

 febrile diseases, such as acute rheumatism, endocarditis etc. 



2) That the bursa is capable of facilitating the extension of any 

 endocardial process along the course of the conducting system on 

 account of its anatomical relationship with the endocardium, and of 

 the fact that even small twigs of the auriculo-ventricular bundle which 

 lie immediately under the endocardium are surrounded with cellular 

 tissue, the spaces of which are continuous with the main bursa. 



3) The existence of the bursa tends to prove that either the 

 auriculo-ventricular bundle does not contract at all, or that it con- 

 tracts in a different way and at a different time from the con- 

 traction of the ventricle. 



4) The striking gross resemblance of the reticulum in the calves' 

 and sheep's hearts to a nerve ganglion, when dissected out as shown 

 in plates VI and VIII, and its connection with all parts of both 

 auricles through three large trunks and a number of smaller twigs 

 and not, as was once throught, merely arising in the right auricle 

 only. These connections point to the possibility of the contraction 

 wave either beginning in the reticulum and proceeding through its 

 branches to all parts of both auricles, or to its coming from all parts 

 of both auricles to meet at the reticulum. In this case there would 

 be a probability of each auricle controlling the time of contraction of 

 the corresponding ventricle, and the meeting at the reticulum of the 

 various bundles of fibres from both auricles and proceeding thence to 

 the ventricles as the auriculo-ventricular bundle, would merely mean 

 an economy of space. 



5) The accessory ventricular branch of the reticulum must be 

 counted on in physiological experiments. 



My thanks are due to Professor Dwight for his encouragement, 

 assistance and valuable suggestions which have greatly helped one in 

 the course of this study. 



Anat. Adz. XXXV. Aufsätze. 



