322 JAMES EDWARD ACKERT 



way in which the nerve fiber ended in the interior of .the bulb. 

 He observed that medullated nerve fibers divided at Ranvier's 

 nodes, giving off several medullated branches. Occasionally, 

 one of these branches entered an end-bulb, and passed through 

 the whole interior of the organ to its opposite extremity. This 

 naked axis cylinder in the bulb became slightly expanded, and 

 ended either with a sharp point or in a thickening resembling 

 a button. 



Sabussow, in his figure 10, pictured an end-bulb stained with 

 methylene blue, which he called a variation of the cylindrical 

 end-bulb type. He described it as follows: 



Within the bulb the axis cylinder expands, and, in the middle, 

 broadens into a wide, paw-like plate with deep notches in its edges. 

 From this plate there is given off a fiber which bends backward and 

 upward, and in turn widens into a similar paw-like plate. The sub- 

 stance of the plate has a granular appearance, with here and there 

 small masses of stain. 



In my own methylene blue preparations of the integument 

 two kinds of special sensory end-organs have been observed. 

 (1) A small elongate end-bulb into which a single medullated 

 nerve fiber enters, passes approximately to the opposite end, and 

 terminates in a sHght enlargement (fig. 18) ; (2) A large, round, 

 cellular corpuscle innervated by a single fiber which disappears 

 among the cells of the organ (figs. 19, 20). A more detailed de- 

 scription of each type follows. 



a. End-bulbs. These structures occur in the corium near 

 hair follicles, but clearly outside of the root sheaths. Ordinarily 

 they are found below the level of the sebaceous glands, parallel 

 with the long axis of the hair. Their size is approximately 1.5m 

 in length by 0.5m in width. In general appearance they are 

 regularly club-shaped in outline, the interior being filled with a 

 semi-fluid substance. The medullated nerve, on entering the bulb, 

 loses its myelin, the sheath of which becomes continuous with the 

 sheath of the end-bulb. After passing through half the length of 

 the organ, the axis cylinder expands slightly into a flat plate 

 (fig. 18, p) which gives off two or three short heavy branches, and 

 terminates near the end of the bulb in a small enlargement 



