IXTRODUCTION
Spinal ganglia have been transplanted by Uarinesco, Agosti, Nageotte, Ranson, Cajal, and others. The conditions under which the experiments were performed varied somewhat and there have been some differences in the results reported. Since the literature on this subject has been reviewed fully by Cajal ('as), specific reference will be made only to two contributions which are directly related to the experiments which follow.
Ranson ('14) transplanted the spinal ganglia of white rats into the cerebral cortex of other individuals. He divided his experiments into two groups. The first group included transplants of two, three, and four days. In this group he observed that there were a few surviving cells at the periphery. These cells stained darker than the dead ones and in some cases showed a neurofibrillar network. Surrounding the surviving cells was a group of new-formed fibers. I n some cases the original axon could not be made out, but the new fibers assumed several arrangements, among which pericellular plexuses were seen. Many of the fibers showed swellings along their courses and many terminated in end bulbs or rings. He stated that the fine fibers arose from the cell body directly or from the coarse branches.
' Contribution no. 167.