194 BOTANICAL GAZETTE [SEPTEMBER 
ments with defoliated stems gave the same results as have 
already been described for Atrichum. 
Mention may be made here of the cultures of Pogonatum 
nanum leaves. Cultures of these leaves were kept for two months 
without any appearance of protonemata, although the leaves were 
apparently vigorous. 
8. BRACHYTHECIUM RUTABULUM. 
The leaves of Brachythecium did not produce protonemata 
with very great readiness, only about one out of every eight 
giving rise to protonemata. The first production of protonemata 
was noted at the end of nearly three weeks. As in the case of 
Bryum the first growth was neither distinctly protonemal nor 
rhizoidal. Even in the cultures in the light the main axis soon 
changed its cell walls to a well-marked brown, while the side 
branches continued as distinctly protonemal, with generally 
perpendicular cross-walls, and an abundant chlorophyll content. 
Buds were formed very soon and consequently the protonemata 
did not attain any considerable size. In the cultures in the dark 
the filaments remained long and occasionally branched, with 
brown cell walls, oblique cross-walls and no chlorophyll. Buds 
were found after about three weeks, but these were confined to 
the cultures which had been exposed to the light. The buds 
originated in all cases as side branches of the main protonemal 
axes, 
The first experiments with the leaves showed that the proto- 
nemata originated exclusively from the larger cells lying next 
the very base. None of the cells removed from the periphery 
gave rise to a growth, but only those one side of which was next 
the free lacerated base of the leaf. Leaves were cut transversely, 
and also longitudinally and all portions placed in conditions 
favorable for growth. The apical half of the leaf gave rise to 
no protonemata whatever, while the basal half only produced 
protonemata from the proximal end, with an origin the same as 
in the cases of the whole leaves. The portions of the leaves 
which had been split longitudinally also gave rise to protone- 
