1898 } REGENERATION AS EXHIBITED BY MOSSES 189 
of the main axes after a time turned brown and had more of a 
rhizoid nature. The side branches, although at times slender 
and tapering and now with oblique cross-walls, now with per- 
pendicular walls, were decidedly protonemal in character and 
possessed an abundant chlorophyll content. <A thick net of 
interlacing protonemal filaments was obtained from the culture 
in the light. At the end of ten weeks the network was several 
centimeters in extent, and notwithstanding the fact that it had 
been exposed to the light in the laboratory window, no bud for- 
mation had resulted. The suppression of bud formation could 
not have been due to the lack of sufficient light, since as 
exposed in the window the illumination was quite intense. Up 
to this time the culture had produced no growths which I could 
call rhizoids. The cultures which remained in the dark pro- 
duced only long, very sparsely branched filaments which in their 
further growth tended more to rhizoidal nature, with no chloro- 
phyll, brown walls, and always oblique cross-walls. 
At the end of about eleven weeks the protonemata had given 
rise to distinct rhizoid branches, and an abundance of buds had 
been formed. Soon after this the old protonemata began to 
turn brown and die. During this period of growth, the extensive 
network of protonemal filaments had not been entirely produced 
by the direct growth of the originally formed main axes, but a 
multiplication of the protonemata had occurred. Certain side 
branches seemed to be specialized for this purpose, since the 
cells increased in size, developed a very abundant chlorophyll 
content, rounded themselves somewhat until they were about 
barrel-shaped, and then separated from the branches either 
singly or several together. These separated cells then gave 
rise to new protonemata. Goebel* mentions the power of a 
protonema, species not known, to separate in this way when the 
culture was allowed to dry. In the case of Barbula, however, 
the splitting away of the cells was not due to drying out, since 
the culture was supplied with nutritive solution for the entire 
period of growth. 
*6 Sitz.-Ber. d. mat.-phys. Classe d. k. Bayer. Akad. d. Wiss. 36: 641. 1 896. 
