192 Journal of Comparative Neurology. 



sharply at right angles to their course and entering the spindle 

 from a direction at right angles to its long axis. At other times, 

 the branches turn back to spindles behind their point of branch- 

 ing, forming a long curve not unlike what Cattaneo likens to 

 the branches of the weeping willow. At other times, the nerve 

 approaches the spindle from the same direction as its long axis, 

 when it either enters at the extremity or passes along beside 

 the organ to near the center and then turns sharply and enters 

 the end-organ. In nearly all cases in which the nerve enters the 

 the end-organ near its center, it at once divides into two primary 

 medullated branches, which turn toward the the two extremities 

 of the organ. These fibers may extend with shorter and shorter 

 internodal segments and with few sid6 branches to near the ex- 

 tremities of the organ, before breaking up into a number of 

 finer branches, each of which redivides, the resultant tertiary 

 branches soon becoming non-medullated and terminating as we 

 shall describe later. The few side branches given off nearer the 

 center are either non-medullated or quickly become so and soon 

 terminate in the typical end-arborization. This massing of the 

 end-brushes at the two extremities of the spindle, the center 

 being comparatively free, gives a peculiar appearance, although 

 it is not at all uncommon, especially in the cat. Such a spin- 

 dle is represented in Plate XVI, Fig. 21. At other times, and 

 this may perhaps be considered a more typical form of the end- 

 ing, the nerve fiber divides at once on entering the end-organ, 

 the branches turning toward the extremities of the spindle, but 

 the primary medullated branches are very short and soon divide 

 into a number of secondary branches, some passing back to- 

 ward the center and some on toward the extremities and all 

 quickly dividing into a number of non-medullated fibers which 

 soon form the characteristic plaque. In this form, the equator- 

 ial region of the organ is occupied by a dense and confused 

 mass of terminal ramifications, mingled with the large but short 

 medullated fibers, the whole mass gradually diminishing in size 

 as it approaches the poles. In other end-organs, the nerve 

 branches before entering the organ, or two or more independent 

 nerves enter the organ so that three or four large medullated 



