198 Journal of Comparative Neurology. 



ular, leaf-like enlargements, which encircle the bundles of con- 

 nective tissue making up the tendon fasciculi of the end-organ. 

 The terminal enlargetnents remind us slightly of those found in 

 the simpler ending of the turtle, a characteristic form consist- 

 ing of a broadening and flattening out of the whole axis cylin- 

 der, which becomes granular and is fantastically adorned on all 

 sides by other granular masses of different shapes and sizes. 



In addition to these endings, we see an occasional varicose 

 fibril, winding through the connective tissue and showing none 

 of the terminal enlargements. This simple, varicose fibril, 

 which seems not connected with the proper ending of the end- 

 organ, we have observed occasionally in end-organs from other 

 species of mammalia studied, and it seems to us to have no im- 

 portant relation to the end-organ or the nerve ending therein, 

 but to be perhaps analogous to the fine nerve fibers which Ruf- 

 fini has described in the end-organs of the cat as forming a 

 '' retiade netveux'' and ending on the striated muscle. It has 

 occurred to us, however, that they may be vaso-motor fibers of 

 the arterioles of the end-organs, only partly stained. 



Longitudinal sections of the neuro tendinous end-organs of 

 mammalia, as sketched in Plate XVIII, Figs. 27 and 28, show 

 that the varicose fibrils, while slightly undulating, often lie 

 upon the tendon fasciculus, and may seem to pass between two 

 adjacent bundles, but never seem to form a complete spiral. 

 The terminal plates are seen to pass between the tendon bun- 

 dles. The character of the ending appears the same as in sur- 

 face preparations. 



In cross sections, as illustrated in Plate XVII, Figs. 25 and 

 26, we see a thin connective tissue capsule, enclosing a variable 

 number of tendon fasciculi, which stain readily and show nuclei 

 more frequently than the adjacent tendon. In other cross sec- 

 tions of the series, the fasciculi seem broken up into smaller 

 tendon bundles, which may or may not be surrounded by loose 

 connective tissue. As Ciaccio has said, and as our sections show, 

 the nerve branches run in the connective tissue binding the small 

 bundles of tendon fibers together, finally penetrating the fasci- 

 culus and partially surrounding the smaller bundles. The ring de- 



