644 HUBER. [Vol. XI, 



The rapid return of function obtained in the first of the 

 above four experiments is rather surprising. There would, 

 however, seem to be no reason why Assaky's interpretation 

 should not be accepted. In one of my own experiments, 

 where an ulnar nerve was resected to the extent of 6 ctm., and 

 a "suture a distance" applied, there was no regeneration at 

 the end of thirty-nine days. This may be owing to the fact 

 that in my experiment the down-growing axis cylinders met 

 with greater resistance, as no doubt the connective tissue 

 developing around the catgut threads had an opportunity to 

 become more firmly organized before the developing axes could 

 reach the peripheral end. By way of explanation, I may state 

 that, in all cases of division of a peripheral nerve, the regener- 

 ation of the peripheral end depends on the outcome of a 

 struggle between the down-growing axis cylinders and the 

 developing connective tissue between the severed ends, a fact 

 which I hope to show later on in this paper. 



This method has further been experimentally tried by 

 Willard, by whom four operations are reported. The results 

 are as follows : — 



From the right sciatic of a black pup % inch was removed. The 

 divided ends were stitched with fine chromatized catgut, purposely leaving 

 them % inch apart. After forty-six days the dog was killed. The site 

 of operation upon the nerve was distinguishable only by a slight enlarge- 

 ment, and to the naked eye there apparently had been union. The 

 microscope showed that only one bundle of the nerve trunk had been 

 severed. The ends of the divided portion had separated yi inch, and were 

 united by fibrous tissue, scattered through which were found many nerve 

 fibres. Judging from the figure (No. 2) given by Willard, the new fibres do 

 not seem to have reached the peripheral end of the nerve. The left side of 

 the same dog was operated upon the day following the first operation ; ^ 

 of an inch was removed from the sciatic, and a bundle of catgut strands was 

 stitched between the ends. Microscopical examination showed the upper 

 fragment ending in a bulb of fibrous tissue containing numerous nerve 

 fibres, these radiating from the termination of the nerve fibres. The 

 peripheral fragment was degenerated, the new fibres not having penetrated 

 it. (See Fig. i of Willard's article, which represents a longitudinal section 

 of the nerve operated upon in the second experiment. The central fibres 

 of the stump are shown in the process of growing down toward the 

 peripheral end ; it would seem safe to assume that in time regeneration 

 would have been complete.) In two other experiments of implantation of 



