680 A. fF. Goldfarb 
so very large that it gave the impression from an external examina- 
tion, of a regenerated tail, and in fact was so designated in my 
notes. Examination showed however that this cap contained 
neither cartilaginous skeleton nor nerve cord, and can therefore 
hardly be called a tail. The tail was in all probability about to 
develop. 
In 14.21, 8 mm. of the cord was removed and in 79 days a new 
tail had actually developed 3 mm. long. 
Anterior to the roth mm. the nerve cord was normal. Between 
this and 84 mm., the fibrous layer had degenerated, and the cord 
in this region had shrunken considerably. The cord thins very 
gradually to and beyond the amputated end to the very tip of the 
regenerated tail. Here too, no sharp line can be drawn between the 
old andthe newcords. Neither in this nor in any of the preceding 
animals were medullated fibers differentiated in the injured region. 
The neural arch proliferated cartilage, that cemented broken 
pieces together and formed irregular masses within the arch, and 
in this animal grew distally to constitute the skeleton of the new 
tail. 
In more than fifty other animals the cords of which had been 
removed from the tail region alone, or from the tail and lumbar 
regions, the cord was found in every instance, on subsequent 
examination, completely absent from the neural groove of the oper- 
ated area, and in every case a new tail failed to develop. Similar 
reparative changes already alluded to were observed, such as the 
formation of multiple cords, etc. 
In the following table a number of the animals are arranged 
according to the extent of the regenerated nerve cord. 
We might assume that the diminutive new cord, quite embryonic 
in character, transmits nerve impulses either through embryonic 
fibers too minute to be detected or through the protoplasm of 
surrounding tissues, and that this nerve stimulus induces regenera- 
tion. If this be so, it is quite difficult to understand why it is that 
these impulses do not suffice while the cord is growing toward and 
ever so close to the amputated end. But as soon as the cord 
actually reaches the end, regeneration begins. 
