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ZOOLOGY: S. R. DETWILER 
THE EFFECTS OF TRANSPLANTING LIMBS UPON THE 
FORMATION OF NERVE PLEXUSES AND THE 
DEVELOPMENT OF PERIPHERAL NEURONES 
By S. R. Detwiler 
OsBORN Zoological Laboratory and Anatomical Laboratory, School of Medicine, 
Yale University 
Communicated by R. G. Harrison, June 6, 1919 
Previous experiments on the transplantation of limbs (Braus,^ 
Banchi,2 Gemelli^ and Harrison^) have shown, with the exception of 
those of Banchi, that limbs placed in an abnormal (heterotopic) posi- 
tion will acquire a system of peripheral nerves derived from that part 
of the central nervous system of the host which corresponds to the posi- 
tion of the implanted limb rudiment. That such nerves may be par- 
tially functional has been shown both by slight spontaneous movements 
of the limbs and by movements in response to electrical stimulation. 
The majority of the experiments to which reference has just been 
made were carried out upon anuran embryos at a period when the 
peripheral nerve paths were in part or wholly laid down. Accordingly, 
the limb rudiments were placed in the direct pathway of one or more 
developing spinal nerves which merely continued their growth into the 
rudiment so placed. In all of these experiments the transplanted limb 
was developed from an additional rudiment, taken from another em- 
bryo, the normal limb rudiments of the host being left intact. 
Experiments carried out by the author upon the urodele, Amblystoma 
punctatum, in which the anterior limb rudiment was transplanted to an 
abnormal position at a period prior to initial outgrowth of the spinal 
nerves, strongly suggest that the limb exerts a guiding influence upon 
the segmental nerve supply and determines the path taken by the spinal 
nerves effecting its innervation. The positive reaction towards this 
influence appears to be greater in the nerves developing from the nor- 
mal limb level of the cord than in those developing from more posterior 
segments of the cord. 
Positive evidence has also been found to show that the functional 
activity of the transplanted limb has initiated a hyperplasia of the 
peripheral afferent neurones, the spinal ganglia connected with the 
heterotopic limb being considerably larger than their counterparts 
which do not supply an homologous organ. Evidence that the gan- 
glionic hypertrophy has been brought about by an actual hyperplasia 
