Life-history of Notothylas . 395 
The four lower octants develop into the foot, as described 
by Leitgeb 1 . 
The four upper octants are now divided by transverse walls 
into two tiers of cells disposed as quadrants. It is barely 
possible that occasionally three tiers are formed (Fig. 2). Each 
of these cells next divides by a periclinal wall into an inner 
and a peripheral cell. The inner cells become the columella, 
while the peripheral cells give rise to the archesporium and 
the wall of the capsule, precisely as in A nthoceros. This will 
be readily seen by a comparison of Fig. 6 b with Fig. 1 5, 
which are transverse sections of sporogonia of the same age 
respectively. The differentiation of the archesporium from 
the peripheral cells appears to begin at the apex, proceeding 
toward the base (Fig. 3). 
In Notothylas , however, a number of difficulties are met with 
in the demonstration of these facts. Cell-division does not 
follow with as great regularity as in Anthoceros , and the differ- 
ence between the archesporial cells and those of the columella 
is not so pronounced. Here the cells of the archesporium, in 
sporogonia about the size of those in Figs. 4 and 5, are only 
a little richer in protoplasm than those of the columella, 
requiring careful staining and exactly straight sections in 
order to make out the distinction. Considerable difficulty was 
experienced in orienting specimens to get perfectly straight 
longitudinal sections through the sporogonia, from the fact 
that the sporogonia do not stand perpendicular to the surface 
of the thallus, but slightly inclined forward ; and that the 
small lobes of the thallus do not invariably lie flat, but they 
are more or less tipped by the wrinkling or wave-like folding 
of the thallus in its growth. Besides, all sporogonia are dis- 
posed radially on the circular or semicircular thallus, no two 
lying exactly parallel. Several preparations were obtained, 
however, in which the sections passed exactly straight through 
the sporogonium with the above results (Figs. 3 and 4). 
In all cases observed it was evident that the archesporial 
1 Loc. cit. p. 49. 
E e 2 
