EESTOEATION OF CO-ORDINATED MOVEMENTS AFTER NERVE SECTION. (599 



certainly paralysed all the muscles below the knee-joint, and the recovery of voluntary 

 flexion and extension of the paw, and at the tibio-tarsal articulation, implies regained 

 conductivity of the sciatic, as there is no other nerve entering the leg which could 

 possibly have taken up its function. The prompt muscular responses elicited by 

 stimulation of the nerve above, below, and on the cicatrix, also prove that the muscles 

 were still innervated through this nerve. 



The early return of function is adequately explained by the view of regeneration of 

 nerves which I have already elsewhere # advocated, namely, that the young nerve fibres 

 are formed in the peripheral segment simultaneously with the degeneration process, and 

 that they become connected with those of the central segment by means of young fibres 

 formed in the cicatrix from cellular elements which have migrated into the cicatrix from 

 both ends of the nerve, the cellular elements in question having been derived by 

 proliferation from those of the sheath of Schwann. 



The uniform time at which function commenced to return, and the uniform rate 

 with which improvement advanced are, I think, explained by the fact that in all cases 

 the wounds healed without becoming septic, a result due not only to the strictest anti- 

 septic precautions, but also to the complete immobilisation of the entire limb while the 

 process of healing was in progress. A nerve may certainly unite, and conductivity 

 ultimately be restored, even although the wound becomes septic, a fact of which I have 

 recently obtained clinical proof, but the return of conductivity is in such cases un- 

 certain ; it may never return, but if it does so, is much delayed. But if the wound 

 runs an aseptic course, the experiments would seem to show that return of function 

 takes place uniformly, and equally so whether the two ends are united in their old 

 relationship or not. 



The uniform manner in which return of co-ordinated function was established in the 

 experiments might be hypothetically explained in different ways. Thus it might be 

 supposed that in the cicatrix in Exp. I. and II. , which formed between the two 

 divided ends of the nerve, crossings of the young nerve fibres were effected so as to 

 place the corresponding nerve fibre segments in connection. This view need not imply 

 such an improbable thing as inherent faculty or instinct in the nerve fibres to grow 

 towards their appropriate peripheral segments, but might possibly be brought about in 

 a way more in accord with natural processes. Thus, at the earliest stage of develop- 

 ment of nerve fibres in the cicatrix, when the spindle-cells derived from the immigrated 

 neuroblasts were making connections one with the other, it is conceivable that the 

 nervous impulses would at first pass into the network of spindles in the cicatrix, and 

 be communicated to the fibres of the peripheral segment diffusely, the impulse passing 

 along a single central fibre being diffused through many or all of the nerve fibres in the 

 peripheral end. On such a supposition it is possible that the old path in the peripheral 

 segment would be the easiest for the passage of the impulses, and that the connections 

 in the cicatrix which established the passage between the corresponding ends of the 



* Loc. cit. 



