700 HUBER. [Vol. XI. 



bulbous enlargements. These larger segments are often found 

 free in the proliferated protoplasm filling the sheath. About 

 some of them are found layers of fine granules concentrically 

 arranged, stained like the fragments of the axis cylinder ; they 

 may show the manner in which the axis cylinder segments are 

 resolved. The shorter "axes segments" are as a rule sur- 

 rounded by a thin layer of myelin of a yellowish color. In the 

 above preparation polynuclear leucocytes are found in large 

 numbers between the nerve fibres, and between the ends of 

 the implanted segments and the stump of the ulnar. The 

 spindle-shaped cells ("specific nerve granulation cells"), de- 

 scribed by Gliick as developing between the cut ends of a 

 nerve, and as uniting the central and peripheral axis cylinders, 

 were in no case observed. During the fourth and fifth days 

 degeneration begins in the peripheral end of the divided nerve. 

 The myelin and axis cylinders begin to be broken into frag- 

 ments, and some of the nuclei of the sheath of Schwann are in 

 process of karyokinetic cell division. An inevitable result of 

 the fragmentation of the axis cylinders is the loss of the con- 

 ductivity of the fibres in the peripheral nerve, as shown by 

 the fact that they do not carry impulses when stimulated with 

 induction shocks or mechanically. The permeation of the 

 polynuclear leucocytes, as observed in the implanted segment, 

 was not observed in the degenerating peripheral ulnar. 



During the sixth, seventh, and eighth days, fragmentation 

 and absorption of the myelin and axis cylinders of the fibres in 

 the implanted segment goes on so rapidly that by the end of 

 the ninth day it becomes very difficult to recognize the im- 

 planted nerve. At this time the nearly collapsed sheaths of 

 Schwann take a green stain (tissue hardened in Flemming's 

 solution and stained in safranin and licht griin), and contain a 

 protoplasm in which are found a few granules faintly tinged 

 with the safranin (see PI. XXXIV, Fig. 4). At rare intervals 

 the observer meets larger or smaller balls of myelin stained 

 black with the osmic acid. One such fibre is shown in the 

 figure ; at either side of the myelin fragments the tubular 

 sheath becomes rapidly smaller, and resembles in structure the 

 other fibres reproduced. The nuclei of the sheath of Schwann 



