BV? ELIZABETH HOPKINS DUNN 
The possible relations of these transplanted neurons with 
neurons outside of the transplanted portions have not been de- 
termined by the results of these experiments. In no brain of 
the four, with successful transplants, did the transplanted bit 
so attach itself that fibers could cross the line of attachment to 
unite functionally with adjacent neuron masses. 
The two points of chief importance in successful cerebral 
transplantation are first, the retention in place of the material 
transferred, and second, the furnishing to it of an adequate 
blood supply. Apparently the death of neurons in blocks of 
transplanted cerebral cortex has been due to some factor which 
has not affected the vitality of other tissues. The supporting 
tissues of the cortex have lived and retained the mass form of 
the transplanted bit. This may suggest the lack of sufficient 
nourishment for the nervous elements. In my own successful 
operations, the transplanted portions have remained adherent 
to the denuded portions of the cortex but have taken some 
position near the choroid plexus of the lateral ventricle and have 
apparently received their blood supply from that source. Dr. 
Ranson permits me to mention that in carrying on some further 
(unreported) studies in the transplantation of nerve ganglia 
into the brain he found the most nearly normal conditions in 
those ganglia which were within or adjacent to the choroid 
plexus. This may have been due to the more complete anchor- 
age of the material or to a more adequate nourishment, and 
my own experience would put emphasis on the latter reason. 
It would seem then that after the mechanical difficulties of 
securing juxtaposition have been solved, the viability of the 
transplanted tissues will be secured by guaranteeing sufficient 
nourishment. 
My chief reason for believing these four to be true trans- 
plantations of cerebral cortex is the finding in each instance a 
line of cicatricial tissue about the mass of cortex in question. 
To follow the enclosing cicatrix it was necessary to study serial 
sections, and to assure oneself that the tissue mass in ques- 
tion was not partly separated from the remainder of the brain, 
or a bit which had been twisted out of its original position in the 
