34 



JOHN SZENTAGOTHAI 



the contralateral motoneurons, but these according to the findings of Curtis, 

 Krnjevic and Miledi (1958) may be considered as excitatory ones. 





Fig. 1. Degenerated dorsal root collaterals in ipsilateral motor nucleus in S3 level 

 4 days after transection of dorsal root 53. Cat. Nauta method, x 1350. 



Fig. 2. Part of Fig. 1 with higher magnification. 2700. 



Fig. 3. Contralateral motor nucleus in 53 level 4 days after transection of dorsal 

 root 53. No signs of degeneration around motor neurons. Same slide as Figs. 1 and 



2. > 2700. 



Fig. 4. Few degenerated fragments (indicated by arrows) found in contralateral 



motor nucleus 53 after transection of dorsal root 53. Compare size and distance 



of fragments with Fig. 2 of same magnification. Same slide as Figs. 1 and 2. 



Fig. 5. Oculomotor nucleus 5 days after focal electrolytic lesion in the region of 



Darkschewitsch's nucleus. Degenerated very thin fibre indicated by arrows 



Bielschowsky-Gros method. 3000. 



Fig. 6. Isolated motor horn preparation of the segment L? in the dog. intact fine 

 fibre closely attached to motoneuron dendrite. Bielschowsky-Gros method. 3000. 



