1898 | REGENERATION AS EXHIBITED BY MOSSES 199 
The dorsal side of the costa was made up entirely of thick-walled 
cells, hence no oe production from the dorsal side 
occurred (fig. 51). 
Whole plants and saints with the tips of the leaves cut away 
produced no protonemata from the leaves, nothing but a com- 
plete separation of the leaves from the stems being sufficient to 
call forth the formation of protonemata. The protonema pro- 
duction from the costal region occurred throughout the entire 
extent of the leaf, but that from the apical portion was greater 
than that from the basal portion. 
The defoliated stems produced protonemata directly through- 
out their entire length, and they were not confined entirely to 
the leaf axil, any of the surface cells being capable of growth. 
The defoliated stem generally produced at least one new shoot, 
and sometimes this originated from the very base of the stem, 
sometimes from nearer the apex. Whole plants placed in exactly 
the same conditions produced protonemata directly from the 
stem, and also new shoots. — 
II. CERATODON PURPUREUS. 
All attempts to obtain protonemata from the leaves of Cera- 
todon were without effect. The leaves were kept for several 
months in apparently vigorous condition without any sign of 
protonema formation. The defoliated stems are however able 
to give rise to an abundant protonema growth, which originated 
direct from the region of the leaf axils. Rhizoids were also 
produced, but they very soon became protonemal in nature in 
the cultures which are exposed to light. In the dark the 
growths were of a more rhizoidal nature, and generally remained 
almost devoid of branches. The protonema production was not 
local but was general throughout the entire length of the stem. 
The defoliated stems also produced new shoots as lateral branches. 
The point of origin was not definite, since they might come at 
any point between the base and apex of the stem. The produc- 
tion of new shoots occurred as well in darkness as in light. 
Whole plants placed in the same conditions as the defo- 
