570 ELIZABETH HOPKINS DUNN 
adjacent parts ot the hemisphere. This splint would be, I 
believe, an important factor in ultimate success. 
The operation was done under ether anaesthesia and the 
animal kept warm, both during the operation and for two or 
three hours after the operation, until it had thoroughly recov- 
ered from the anaesthetic, and the odor of the ether from the 
anaesthetic and from the collodion dressing had disappeared. 
Then the young rats were returned to the nest and met with no 
interference from the mother other than futile attempts to re- 
move the collodion dressing. The quiet and seclusion of the 
nest during the few days after operation aided convalescence. 
Young rats are not inclined to stray from the nest until the 
eyes open, about the fourteenth day of life. 
EXAMINATION OF THE MATERIAL 
No microscopical studies of the early conditions of the trans- 
planted material were attempted, as the attention was cen- 
tered on an effort to ascertain whether such transplanted ma- 
terial would later contain mature neurons with medullated 
axons. The brains of a few rats which died soon after operation 
gave no suggestion of the survival of the transplanted tissue. 
A few of the operated brains especially from the rats of the 
earlier operations, showed some inflammatory changes, with 
disintegration of the cerebral substance, about the region of the 
incision. 
The rats upon whom these experiments were carried out gave 
the appearance of normal rats. No convulsions or paralyses 
were noted in the operated animals. Control rats were studied 
during the course of the first operations but, when no sequellee 
of the operative procedure were noted, the observation of 
control rats was abandoned. 
The examination of the material removed post-mortem was 
of two kinds. The first of these was the gross examination at 
the time of autopsy, when notes were made regarding the con- 
dition of the skull, of the meninges, and of the cerebral substance 
as to the superficial extent of the wound, location of the cica- 
trix, et cetera. The brains were then removed and fixed in 
