196 BOTANICAL GAZETTE [SEPTEMBER 
more and more the protonemal character. Towards the distal 
end the cells were much shorter, abundantly filled with chloro- 
phyll, and with perpendicular cross-walls. Even in the light 
the branching remained suppressed and only long, unbranched 
filaments about 1° long were produced. In the cultures in the 
dark the filaments remained distinctly rhizoidal in nature and 
reached the length of about 1™ after four weeks of growth. 
When leaves which had remained in the dark for about four 
weeks were placed in the light, the continued growth of the 
rhizoids soon became of a more protonemal character, so that a 
direct transformation of the main rhizoid axes to protonemata 
was called forth. Even in this case no branching resulted and 
no buds were produced, either in the light cultures or in the 
dark. 
The protonemata originated from the basal portion of the 
leaf and generally from some of the cells a little removed 
from the end. There was no inherent tendency to the produc- 
tion of protonemata from a particular side of the leaf. And, 
moreover, the growth occurred now from the contact side, now 
from the free side. In order to determine whether the cells 
removed from the base-had the power of producing protone- 
mata, the leaves were cut transversely and kept in condition 
favorable to growth for about two months. No growth resulted 
from the apical portion, and from the basal portion the growth 
was the same as in the whole leaf. These experiments showed 
the power of growth to be localized in the cells of the basal half 
of the leaf. It was also shown that the production of protone- 
mata was only called forth by the complete separation of the 
leaf from the stem. 
Defoliated stems when kept in culture a short time produced 
an abundance of rhizoids and protonemata from the region of 
the leaf axils, the protonemata generally being the more abun- 
dant. In the dark all of the growths from the stem retained the 
nature of rhizoids, but when exposed to light the further growth 
was of a decided protonemal character. The protonema pro- 
duction was not local but occurred in as great abundance from 
aoe 5 as ai a aiken a eS allat 
