396 BROWN: REGENERATION IN PHEGOPTERIS POLYPODIOIDES 
either in the younger or older stages of their gametophytic or 
sporophytic life history and especially in the younger stages, does 
not always react in the same way to the same environmental con- 
ditions; but each has a sort of individualism which enables it to 
react in the way best fitted for its particular needs. It seems very 
probable that in this particular case regeneration is closely con- 
nected with nutrition for the reason that the severed leaf was not 
able to regenerate immediately another sporophyte, but could 
produce a cellular mass which appeared to be a reversion to a 
prothallus-like structure. This structure after rhizoids developed 
gave rise, in an apogamous manner, first to structures intermediate 
between leaves and prothallia; then, as the number of rhizoids in- 
creased, enlarging the absorptive surface, which in turn increased 
the amount of nourishment, true leaves were produced. The 
first cf these were the ordinary type of young sporophytic leaf but 
later ones were much more primitive in character, due doubtless 
to the lowered vitality of the prothallus-like structure. This 
coincides with Goebel’s (1, vol. 2, Pp. 42) views. He considers a 
reversion to a juvenile form as being the result of unfavorable con- 
ditions to which the plant is subjected. It is also in keeping with 
the results obtained by Miss Kupfer (3, p. 229) in her experi- 
ments, which indicated that at the time of cutting under normal 
conditions reserve food was present in sufficient quantities to 
initiate the first stages of regeneration. If this food was absent 
and its formation prevented regeneration was prohibited. 
Such an explanation as this does not lose sight of the impor- 
tance of the other factors so strongly emphasized by various 
workers, for all these factors doubtless play an important part in 
nutrition. 
Experimental data in this particular case are not extensive 
enough to permit drawing conclusions as to which of the above 
factors or groups of factors acting separately or together, was the 
determining one. However, since an intimate relation exists be- 
tween growth and regeneration and since growth is dependent 
upon nutrition, it would seem as if some phase of nutrition must 
be an important factor in regeneration, 
if not the most important 
factor. 
