ICO 
Humphrey . — The Development of 
The number of neck-canal-cells is, so far as observed, invariably six 
(Fig. 45, PL VI). The mature archegonium is considerably more enlarged 
through the venter than in Porella , and the egg-cell is noticeably larger 
than the central canal-cell in comparison with Porella , corresponding 
more nearly with these cells in Sphaerocarpus. The cells constituting the 
wall of the venter consist usually of one layer, though Text-Fig. 7, A, repre- 
sents a case where two layers occur. Here again F. longiseta differs from 
F. pnsilla as described by Leitgeb 1 , where, according to him, the ventral wall 
is commonly two layers of cells 
in thickness. The development of 
the perianth, as described by him, 
agrees exactly with that of F. 
longiseta , in that it develops only 
after fertilization, the unfertilized 
archegonium bearing at its base 
only a chain or two of cells re- 
sembling somewhat glandular hairs. 
The perianth is always open an- 
teriorly and grows much more 
rapidly than the young sporogo- 
nium, completely hiding it until 
nearly ripe. 
The unfertilized egg has a well- 
defined receptive spot. The rela- 
tively large egg-nucleus, as well as 
the nuclei in other parts of the 
plant, as a rule possess but one 
nucleolus and a small amount of 
chromatin. Text-Fig. 7, B, re- 
presents a fertilization stage in 
which the spermatozoid has entered the egg-cell. Later stages were 
not obtained. 
The neck of the mature archegonium, owing to retarded growth on 
one side, is always more or less curved and inclined, as are the antheridia, 
to the plane of the thallus. Usually a number of archegonia develop, 
but only in rare cases are more than one of these fertilized. Fig. 1, PI. V, 
represents a plant on which two sporogonia have developed, and that, too, 
from parts of the thallus where one would least expect them. Usually 
the development of the sporogonium marks the end of the season’s growth 
for the plant. It is usually situated just behind the growing point instead 
of far back on the thallus as in Fig. 2, PI. V. 
Fig. 7. 
Cross-section through venter of 
mature archegonium. x 560. B. A similar section 
showing presence of spermatozoid in the egg. x 
1200. C. Cross-section of young embryo, x 560. 
1 loc. cit., p. 1 13. 
