724 HUBER. [Vol. XI. 



Cicatricial tissue between the resected ends of the ulnar 

 (Exp. 38) cannot be differentiated into columns of a loosely 

 interwoven tissue, surrounded by layers of a denser fibrous 

 tissue, as was described for preparations made from Exp. 

 37, twenty days after implanting the catgut threads. It pre- 

 sents a structure of about the same density throughout. I am 

 unable to state, whether the new axis cylinders which begin to 

 grow out from the central end about twenty days after suture 

 a distance (at a time when tracts of a looser structure are to 

 be found in the fibrous tissue uniting the resected ends), follow 

 these paths or not. 



In the peripheral portion of the ulnar in Exp. 38, only 

 degenerated nerve fibres, with collapsed sheaths containing a 

 nucleated band of protoplasm, were found. 



In Exp. 39 (of 135 days' duration), regeneration of the 

 ulnar extends to about the middle of the forearm and to the 

 muscular branch of the flex. carp, ul., as in this portion of the 

 nerve newly formed nerve fibres are to be seen in and between 

 the old sheaths of the degenerated fibres. Structurally, many 

 of the nerve fibres consist only of an axis cylinder ; in others a 

 thin layer of myelin is recognized. In the peripheral ulnar 

 from a point a little below the middle of the forearm, only 

 degenerated fibres are found. In Exp. 41 (of 152 days' 

 duration), sections made from any part of the peripheral ulnar 

 show regenerated fibres. In both of these experiments, in the 

 cicatricial tissue uniting the resected ends, bundles of nerve 

 fibres, which have their origin in the central stump, and which 

 can be traced from the connective tissue into the peripheral 

 stump, are found. In the connective tissue the bundles of 

 nerve fibres have a very tortuous course, as may be seen from 

 PI. XXXV, Figs. 20 and 21, made from sections of the tissue 

 supplanting and surrounding the catgut threads in Exp. 

 41. PI. XXXV, Fig. 20, represents a part of a longitudinal 

 section cut from tissue taken from about i ctm. below the 

 central wound. It will be seen that while some of the nerve 

 bundles {a) have a direction which is nearly parallel to a line 

 uniting the central and peripheral ends of the resected nerve, 

 others (^) have, at least for a short distance, a course which is 



