Botrychium simplex , Hitchcock. 
447 
t 
Bruchmann figures several cases in B. lunaria where two young sporo- 
phytes were developed from the same gametophyte ; but no such cases 
were seen in B. simplex , although of course it is quite likely that this might 
sometimes occur. 
After fertilization, the free portion of the archegonium neck usually 
breaks down. The fertilized egg develops a membrane and the unicellular 
embryo soon completely fills the cavity of the venter (Text-fig. 3, a). It 
soon divides by a transverse wall, the 
two cells usually being of approxi- 
mately equal size, but sometimes one 
is longer than the other (Text- 
fig- 3. b )- 
To judge from a not very complete 
series of embryos secured by the 
writer, B. simplex shows an unusual 
amount of variation in the early division 
of the embryo. While the first (basal) 
wall is generally transverse, as it is 
in most Eusporangiatae, it may be 
strongly oblique (Text-fig. 3, c), and 
the succeeding divisions are extremely 
variable. 
In form, the young embryo may 
be globular or somewhat elongated 
either vertically or horizontally (see 
Text-fig. 3). The succeeding divisions 
evidently are extremely variable, but 
the number of young embryos avail- 
able was too small to make it possible 
to determine what is the most common 
arrangement of the cells in the very 
young embryo. Bruchmann shows a regular quadrant and octant division 
for B. lunaria , but none of the embryos of B. simplex showed such regularity 
in the position of the walls of corresponding stages. 
Text-figs. 3, D, E, show two of the youngest embryos seen by the 
writer. E is a three-celled stage, in which the epibasal portion is 
divided by a median (quadrant) wall, the hypobasal part being still un- 
divided. D shows three longitudinal sections of a four-celled embryo, in 
which no vertical walls have yet been formed. 
Text-fig. 4, A, shows three sections of an older stage in which there is 
an approach to a quadrant division, and this embryo corresponds pretty 
closely with that of B . lunaria shown in Bruchmann’s Fig. 39. It is not 
possible to determine at this stage the relation which these early divisions 
/ 
/ / \ 
f\pCf \ 
/ VI 0^ 
B ,-dOJl 
V 1 / J 
\( ° J 
I 
' n 
Text-fig. 4. a. Three longitudinal 
divisions of a young embryo showing a pretty 
regular quadrant division ; b , b, basal wall ; 
r, root-initial (?). x 300. b. Two somewhat 
oblique sections of an embryo of about ten cells, 
x 300. 
