Huber-DeWitt, Neiiro-tendinous End-organs. 193 



fibers enter near the center, divide into secondary and tertiary 

 branches, which soon become non-medullated and terminate, 

 the whole ending resembhng a bush or low tree whose trunk is 

 at right angles to the long axis of the organ. In still other 

 organs, less frequently found, the nerve enters near the extrem- 

 ity and either branches at once or runs for some distance before 

 branching, sending off at intervals side branches with their ter- 

 minal plaques and finally breaking up. into a large number of 

 non-medullated fibers and ending in the typical end-arboriza- 

 tion. This gives a more distinctly tree-like appearance than 

 any of the other forms seen. These are the four principal 

 types of end-organs seen by us in the mammalia studied and 

 they may, any or all of them and many modifications of them, 

 be seen in any of the species examined. They may even all 

 be seen at times in different parts of the same tendon, so that 

 none of them can be said to be distinctive of any species of 

 mammalia nor of any special part of the same animal, the 

 form of the ending depending largely on the accidental ar- 

 rangement of the medullated nerves and their relation to the 

 ending. 



In addition to the nerves found ramifying in the end-organ, 

 nerves may sometimes be seen running through the sheath or 

 capsule of the organ and sometimes fine varicose fibers crossing 

 the organ, whose ending we have not observed, but which seem 

 to be quite independent of the nerve supplying the end-organ, 

 and which may be a part of the '' reticule nerveux" described 

 by Ruffini as occurring occasionally about the neuro-tendinous 

 end-organs of the cat, and terminating on the striated muscle 

 either near the organ or at some distance from it. If so, its 

 occurrence does not seem to be confined to the end-organs of 

 the cat. In the dog, a peculiar long cylindrical form of end- 

 organ seems to predominate, in which the large medullated 

 nerves enter the organ more or less obliquely, divide into two 

 or three medullated branches, which pass nearly unbranched in 

 various directions through much of the length of the organ, 

 giving off at intervals side branches which are either non-medul- 

 lated or quickly become so and there is very little branching of 



