12 The Botanical Gazette. [January, 
tome sections is not clearly differentiated from the inner 
layers of the exospore. The perinium appears perfectly ho- 
mogeneous, and is smooth except upon the ventral surface of 
the spore where it is folded so as to produce reticulated ridges 
which in section have the appearance of spines (fig. 8, 4, ¢.). 
The character of the spore-contents was not especially studied 
beyond noting the fact that the nucleus is quite small, as is” 
usually the case in the spores of liverworts. 
The most peculiar feature of the plant, and one which ap- 
pears to be unique among Hepatice, is the formation of tubers 
by means of which it becomes perennial. These tubers were 
always met with in the older individuals, and in the second- 
ary shoots from the older thallus were also developed after a 
short time. The tuber consists of an oval mass of cells de-_ 
rived from the interior tissue of the thallus, and including its” 
growing-point. These cells are densely filled with coarsely 
granular contents, mostly made up of albuminous. granules 
and oil-drops, very little starch being present. The first in- 
dication of the formation of the tuber is an accumulation of 
granular matter in the interior cells of the thallus just back 
of the apex, and this extends in all directions until it includes 
nearly the whole central region of the thallus, as well as the | 
cells of the growing point. The chlorophyll disappears from 
the cells and sections of the ripe tuber appear white an 
opaque. Surrounding the central tissue is a more or less 
clearly defined dark cortex, which does not, however, extend 
over the cells of the growing point. The whole tuber is sur- 
rounded by a loose brownish envelope composed of the dead 
outer cells of the thallus. The full grown tuber is a flattened 
body from 1-2™ in length and about half as wide. : 
The tubers are obviously a special provision for carrying 
the plant through the long dry season. Specimens kept pet 
fectly dry from May until about the first of October, germi- 
nated promptly when placed in water for a few days. Growth 
begins by the cells near the growing point turning green and 
the latter resuming its activity. The development of the 
young plants from the tubers has not yet been studied in de 
tail, but it is hoped soon that it may be possible. to follow out 
completely the life-history of this interesting form. 
There seems no doubt that the affinities of Geothallus af 
with the lower Jungermanniacee, the Anelateree. 45 
already stated it agrees with Sphaerocarpus in the general 
