REUNION OF NERVES OF DIFFERENT PROPERTIES. 63 



place in nerves after division, and between the divided ex- 

 tremities of two different nerves having the same properties, 

 but that the divided extremity of a motor nerve may be made 

 to form an anatomical and physiological union with the 

 divided extremity of a nerve of sensation, and that both 

 motor and sensitive currents may be conducted through the 

 fibres at the point of union. 



The only remaining point of physiological interest con- 

 nected with the regeneration of the nervous tissue is in- 

 volved in the recent observations of Yoit on the regeneration 

 of the cerebral lobes after removal in a pigeon, and those of 

 Masius and Yanlair upon the anatomical and functional re- 

 generation of the spinal cord in frogs. 



The experiments recorded by Voit, and his deductions, 

 are very curious, and have given rise to a great deal of com- 

 ment and criticism. In one observation, the cerebral lobes 

 were removed from a young pigeon in the usual way, an 

 operation very easily performed, and one which we practise 

 yearly as a class-demonstration. It is particularly stated that 

 the operation was complete, and that the entire posterior 

 lobes were removed. Immediately after the operation, the 

 pigeon presented the condition of stupor ordinarily observed. 

 As he gradually recovered from this condition, he . began to 

 execute a number of mechanical movements, which it is un- 

 necessary to detail fully, in the most extraordinary manner. 

 The animal continued to improve, ceased the mechanical 

 movements, and began to fly about, exhibiting timidity when 

 approached, and, in short, seemed, after a time, to have quite 

 or nearly returned to the normal condition. One thing, 

 however, was remarked : the animal never took food (it was 

 probably kept alive by stuffing, as is frequently done in such 

 experiments). After five months, the pigeon was killed. 

 The cranial cavity was found to be filled with a white mass, 

 occupying the place from which the cerebrum had been re- 



J&urnal de la physiologie ; and, VULPIAN, Lemons sur la physiologic generale et 

 comparee du systeme nerveux, Paris, 1866, p. 280, et seq. 

 105 



