488 DAVENPORT HOOKER 
Coghill’s discovery (13) that the myotomes receive their pri- 
mary innervation from collaterals of the descending processes of 
the motor cells in Amblystoma is also corroborated by the 
conditions found in these frog embryos. 
The primary reunion of the cord by the growth of fibers be- 
tween its two ends, though accompanied by the establishment of 
physiological continuity, does’ not restore its anatomical struc- 
ture to a condition even approaching the normal. The experi- 
ments demonstrate that a regular series of events must take place 
before: this can occur. These steps to complete regeneration 
of the.cord are found to succeed one another in regular order, 
though the end of one process usually overlaps the beginning 
of the next. 
The outgrowth of fibers from the epithelial cells of the canalis 
centralis plays an important part in the form restoration of the 
cord as they provide the framework of the regenerated area. 
They appear almost concomitant with the completion of the 
sensory nerve fiber connection between the two stumps of the 
- cord and arise from cells situated near the closed ends of the 
canalis centralis. Closely following on this process, begins the 
wandering of neuroblasts into the framework of nerve and epen- 
dymal fibers. The number which migrate into the fiber mass is 
less than that found in the completed cord and they are not the 
ones which have given rise to the neuraxes present in the re- 
generated area at this stage. Caporaso (’89) believes that, in 
regeneration of the cord in tritons after amputation of the tail, 
the epithelial cells of the canalis centralis divide to form the 
nerve cells of the new cord. That such is not the sole source 
of the neuroblasts in these frog embryos is certain, but 1t is very 
probable that from these canalis centralis cells some do develop. 
The principal factor in the structural restoration of the regener- 
ated cord appears to be the elongation of the canalis centralis 
and its epithelial cells in each stump. Just behind their apices, 
the two ends of the canalis centralis present a slight widening 
of the lumen surrounded by a dense mass of its epithelial lining 
cells. Their number is much greater here than elsewhere in the 
cord and it is evident that rapid proliferation is going on.. In 
