502 
Campbell — The Development of 
Embryogeny. 
The fertilization of the egg was not studied, as the extremely 
small size of the spermatozoid did not promise satisfactory 
results. After fertilization the egg increases in size, and the 
granular contents become less conspicuous. The primary 
division (basal wall) is transverse, and divides the egg, which 
still retains its elongated shape, into two cells of nearly equal 
height, but the lower one is more tapering than the nearly 
hemispherical upper one. This first division determines the 
separation of the capsule from the stalk, as in the Marchan- 
tiaceae and Sphaerocarpus. The primary wall is followed 
by a similar one in each cell, so that the embryo (Fig. 33) 
consists of a row of four, resembling very closely, as it does 
in the subsequent stages, the corresponding stages of Sphaero- 
carpus \ The lower of the two cells derived from the hypobasal 
half of the embryo undergoes no further division, but remains 
unchanged and easily recognizable for a long time (Fig. 35). 
Vertical walls now arise in all of the upper cells, which usually, 
at least, divide each of them into four nearly equal quadrant- 
cells (Fig. 34). Somewhat later (Figs. 35, 36) the upper part 
of the embryo enlarges more rapidly, and a series of periclinal 
walls is formed separating a central group of cells, the arche- 
sporium, from a single layer of peripheral ones which undergo 
no further periclinal divisions, but persist as the wall of the 
capsule. In the hypobasal cells the divisions are less regular, 
but here, too, there is unequal growth, the central part of the 
embryo remaining narrow, while the lower cells, by repeated 
division and increase in size, form a conspicuous nearly 
globular foot. 
Owing to the small number of embryos available for study, 
it was not possible to determine with certainty whether the 
succession of the divisions in the young embryo given above 
is always exactly the same. Thus it is possible that a part of 
the short seta may arise from the epibasal portion of the 
embryo, as in the typical Jungermanniaceae, but there seems 
to be no doubt as to the hypobasal origin of the foot. Inter- 
