Huber-DeWitt, Neiifo-tendinous End-organs. 187 



them. The fibers and terminations passing in the same general 

 direction while the enlargements are long and generally slender, 

 the side projections being rarely lifted far from the parent stem, 

 gives a rather cylindrical shape to the entire ending, a form 

 which we have not found unusual for the bird, although Ciaccio 

 mentions that he has found it quite rare. In all the endings ob- 

 served in the bird, we have found terminal plaques similar to 

 those described above, but there are variations in the length of 

 the terminal plaque and also in the number of plaques taking 

 part in the formation of the neuro-tendinous end-organ. Some- 

 times the varicosities are so small and closely packed together 

 and the fibril so straight that it resembles somewhat a sprig of 

 mignonette, with its straight slender stem and small, closely 

 packed pedicled flowers surrounding the stem on all sides. The 

 length, thickness and compactness of the terminal plaque differ 

 in the different end-organs and also their number and arrange- 

 ment and hence the form of the entire end -organ. 



Often one or several medullated nerves enter the organ, 

 either at the extremity or in the equatorial region, breaking up 

 near the center into three or four medullated fibers, which 

 spread out, re-divide, become non-medullated, each branch ter- 

 minating in the characteristic varicose end-plaques. Such a 

 spindle is shown in Plate XV, Fig. 13. The spindle is rather 

 short, broad at the center and tapering at the two extremities. 

 Or we may have organs like that represented in Plate XV, Fig. 

 15, where the spindle broadens out at the center, tapering at 

 one extremity, and, at the other, dividing into two parts into 

 each of which the terminal plaques extend. In plate XV, Fig. 

 12, is represented a rather simple ending, which has been so 

 flattened out that the one meduUuUated nerve, with its two pri- 

 mary branches and their seven or eight terminal plaques are 

 spread out all in nearly the same plane and their relation to the 

 tendon fasciculi is not shown. In this end-organ, there was no 

 capsule, or at most, a very imperfect one. While this prepara- 

 tion gives us no idea of the structure of the end-organ, it shows 

 more clearly than any other preparation the character of the 

 terminal plaque. In Plate XV, Fig. 14, is a rather simple end- 



