Regeneration Not Exact Repetition I4I 
Finally, cases are not rare in which a regenerating 
organ alters its form, as in the lizard in which the new 
tail has a skeleton not formed of individual vertebrae at 
all, but of a little continuous, cartilaginous cylinder. 
Now the epigenetic theories explain very easily how 
it comes that the part amputated can follow in its regen- 
eration a shorter road than in its ontogeny (caenogenetic 
regeneration), and how in many cases after completion of 
the process, it may have a form quite different from that 
of the original part. For the remaining part of the body, 
on which the morphologic determination of the ampu- 
tated part depends, is now in the adult state while for- 
merly it was in the embryonic state. 
The altered condition in which it now exerts its 
formative action upon the part in process of regenera- 
tion explains the diversity, not only of the earlier results 
obtained, in which development and regeneration proceed 
in different ways, but also of the final results, in which the 
regenerated part is of abnormal conformation. For the 
differences of conformation which are produced at the 
commencement of the process of regeneration cannot 
always be smoothed out and effaced when, at the end of 
the regenerative process, the condition of the rest of the 
organism from which the formative action is exerted 
upon the part in process of regeneration becomes again 
the same in relation to that latter as at the end of 
normal ontogeny. 
Weismann on the contrary, whose above quoted ex- 
planation is clearly no more adapted to these cases, is 
forced to take refuge in the following subsidiary 
hypothesis : 
vensystems. Zeitscher. f. wissensch. Zoologie. Bd., 65. Zw. Heft, 
1898. P. 229-—235. 
