XXTIT 
WHY IS REGENERATION OF PROTOPLASMIC FRAG- 
MENTS WITHOUT A NUCLEUS DIFFICULT OR 
IMPOSSIBLE?! 
It has been shown with certainty by a series of experi- 
ments that oxygen is necessary for the development of eggs 
as well as for the processes of regeneration. The reason 
for this might be sought, among other things, in the fact 
that, as I have suggested in two previous papers, synthetical 
changes are necessary for these processes, and that the syn- 
theses depend upon the supply of oxygen.’ It is well known 
that when a cell is cut into several pieces only the pieces 
containing a nucleus are capable of regeneration, while the 
pieces without a nucleus soon disintegrate. This has been 
interpreted by assuming that the nucleus contains specific 
formative substances, which it gives off to the protoplasm. 
This conclusion is, however, not binding. It might well be 
possible that the nucleus is necessary only for the accomplish- 
ment of processes of oxidation. The removal of the nucleus 
would in this case be associated with an inhibition or a 
decrease in the processes of oxidation. This would suffice 
to prevent the regeneration of enucleated pieces of the cell. 
I wish now to test in how far the facts at hand agree with 
such a hypothesis. 
To bring about oxidations in living tissues the presence 
of catalytic substances is necessary which either “activate” 
the atmospheric oxygen, or which render the compounds in 
the cell capable of taking up atmospheric oxygen more 
1 Archiv fiir Entwickelungsmechanik der Organismen, Vol. VIII (1899), p. 689 
2“ Assimilation and Heredity,” Monist, 1898. 
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