184 BOTANICAL GAZETTE [ SEPTEMBER 
time the walls of the main axes turned brown, and the chloro- 
phyll content disappeared, so that eventually the main axes, even 
though exposed to the light, came to resemble rhizoids. With 
the continued exposure to darkness the filaments soon became 
brown; no chlorophyll was formed, and the lateral branching 
was very generally suppressed. In the cultures in the dark no 
buds were formed, while in the light cultures the first buds were 
noticed at the end of seven days, with the more abundant pro- 
duction as growth continued. The buds originated as side 
branches of the main axis soon after the filament had grown 
from the leaf cell. In the further growth the buds appeared at 
different points along the main axis and were homologous with 
the lateral protonemal branches. The lateral branches might 
also in their turn give rise to buds as lateral branches, and after 
six weeks an enormous number of new plants were produced in 
this way. 
The protonema production occurred generally from the cells 
of the leaf base, either from the marginal cells or from those of 
the lacerated base, more generally than from the cells in the 
interior of the leaf. Although protonemata originated from the 
cells removed from the periphery, no distinct tendency to pro- 
duction from a certain side of a leaf was noted. Part of the 
protonemata would originate from the contact surface and part 
from the free surface, sometimes more from the contact surface, 
sometimes more from the opposed surface, so that no constant 
effect of contact was demonstrated. Leaves which had remained 
in the dark for two weeks had produced long, sparsely branched 
rhizoids without any signs of buds. They were then placed in 
the light, and after the lapse of ten days abundant protonemal 
branches were produced from the distal portions of the rhizoids, 
and also an abundance of buds, thus showing that light was 
necessary for the formation of buds. Luxuriantly growing 
protonemata without any buds were placed in the dark and 
allowed to remain for two weeks. The specimens were grown 
upon pieces of flowerpots, and at the end of the two weeks no 
buds had been formed, although the protonema from its previous 
