BROWN: REGENERATION IN PHEGOPTERIS POLYPODIOIDES 393 
the soil cultures became appressed to the soil as a result of acci- 
rents in watering. 
Only one case of regeneration was obtained, although a large 
number of leaves were experimented with. Regeneration began 
in about six weeks after the leaf had been removed from the sporo- 
phyte and laid on sand moistened with Knop’s full nutrient solu- 
tion. One side of the petiole, near its base, was destroyed by 
decay, and a short distance above this point on the opposite side 
of the petiole a slight swelling occurred, from which a cellular mass 
developed. At first it was slightly elongated, Fic. 1, afterwards 
it became much thickened and broadened, Fic. 2, and finally as- 
sumed the shape shown in Fic. 3. From this cellular mass there 
developed two intermediate structures between leaves and pro- 
thallia, then rhizoids and four normal leaves. Neither a true root 
nor a stem “‘ Anlage’’ was formed. 
The first of the intermediate structures resembled a very much 
elongated prothallium, one cell in thickness, with an expanded 
heart-shaped apex. Tracheids arranged in rows resembling a true 
midrib extended up through the portion of the structure corres- 
ponding to the petiole into the expanded or blade-like part. Here 
the rows of tracheids branched dichotomously one branch going 
to each lobe (Fics. 1 and 2). The margins of both the elongated 
and expanded regions were for the most part smooth, with the 
exception of two papillae, one of which developed on the elongated 
and one on the expanded part. 
The second intermediate structure which developed from the 
cellular mass was even more thalloid in form and structure than 
the first one. Both the elongated and broadened portions like 
those of the first were only one cell in thickness. The expanded 
portion differed somewhat in appearance as it was not so distinctly 
heart-shaped and its margin bore many more papillae. There 
were no indications of tracheids present in either of the portions 
representing petiole or blade. 
Growth was rapid and apparently normal in both of these in- 
termediate structures, but the second one never attained the size 
of the first. Neither was long-lived, death occurring soon after 
the normal leaves began to develop. The rhizoids resembled in 
every way those of a normal fern gametophyte. They formed from 
