702 RESTORATION OF CO-ORDINATED MOVEMENTS AFTER NERVE SECTION. 



coaptation of the two segments is effected in the old relationship, the simple approxima- 

 tion of the two ends, no matter in what relationship, being all that is required. 



In conclusion, I have to express my thanks to Professor M'Kendrick and to 

 Professor Young, in whose laboratory the histological work was done, for much valued 

 counsel in connection with this research, and to Principal M'Call, of the Glasgow 

 Veterinary College, who granted every facility for conducting experiments. 



EXPLANATION OF PLATES. 



Plate I. 



Fig. 1. Experiment I. Division of left Sciatic Nerve, rotation through a semicircle of peripheral 

 segment, and suture in that abnormal relationship of the two segments. Shows the dog thirty-one days after 

 the operation. The left hind leg is in the position in which the dog itself placed it. The normal positions of 

 the paw and at the tibio-tarsal articulation are exhibited. The cicatrix of the operation wound is indicated in 

 the area which was shaved before operation, and on which, when the photograph was taken, the hair had not 

 yet grown. 



Plate II. 



Fig. 2. Experiment I. Longitudinal Section of the nerve cicatrix fifty-four days after section. A 

 fasciculus of nerve fibres of the central segment is shown at the upper part, and the corresponding fasciculus 

 of the peripheral segment on the opposite side at the lower part of the section. In the middle line of the 

 section the fibres are almost traceable across the cicatrix, but in other parts the structure is that of a neuroma, 

 and the course of the nerve fibres, therefore, not traceable. 



Zeiss, Obj. a. — . 



Fig. 3. Experiment I. Portion of same longitudinal section from which fig. 2 was prepared. Shows 

 the neuromatous structure displayed in a large part of the cicatrix, in which the continuity of the nerve fibres 

 across the cicatrix is not traceable. Shows some fibres longitudinally, but not traceable for any great 

 •distance, and others cut transversely. 



Zeiss, Obj. D. ?29. 



Plate III. 



Fig. 4. Experiment I. Longitudinal section of central segment of reunited sciatic close to the cicatrix. 

 Shows adult medullated nerve fibres. 



Zeiss, Obj. D. ?J2. 



Fig. 5. Experiment J. Longitudinal section of peripheral segment of reunited sciatic close to cicatrix. 

 Show8 young nerve fibres, and no adult medullated fibres, demonstrating that restoration of conductivity of 

 the nerve was the result not of union by "first intention," but of regeneration of the peripheral segment. 

 The same structure is exhibited also in the terminal divisions of the nerve. 



Zeiss, Obj. D. — . 



