399 
Life-history of Notothylas. 
eusporangiate Ferns as Aiigiopteris 1 . Leitgeb 2 states that 
the lateral walls of the neck-canal-cells during the process of 
growth become very strongly thickened, and this thickening 
extends to parts of the cap (Deckelchen) and even to the 
central cell ; that they are finally transformed into a gela- 
tinous layer, while the cross-walls remaining very thin are 
completely dissolved. It seems to me that the lateral walls 
are not thickened at all, but the phenomenon is due to the 
presence of a swelling mucilaginous substance derived from 
the ectoplasm of the cells (Figs. 22, 2 3). This mucilaginous 
formation begins, it is true, at the ventral canal-cell, and 
proceeds upward. Very frequently, however, the egg is 
surrounded by a mucilaginous formation staining deeply with 
Bismarck- brown, while that in the neck stains only very 
slightly. The ventral canal-cell is usually as large as the 
egg in the mature organ (Figs. 22, 23). 
In one case observed the large cap-cells projected con- 
siderably above the surface of the thallus (Fig. 24). 
The Antheridium. 
In regard to the antheridium, I am forced to the conclusion 
of Waldner and Leitgeb 3 , that this organ arises from a 
hypodermal cell, and that, if the mother-cell be, in any case, 
epidermal and become grown over later by the surrounding 
tissue, this process takes place at a time when the mother- 
cell cannot be distinguished as such. 
Special care was taken in working out this particular detail, 
and in all the youngest stages recognizable, the mother-cell 
was found beneath the epidermis. Fig. 25 shows two mother- 
cells formed by the longitudinal division of an original 
mother-cell. It will be seen that the formation of the cavity 
in which the antheridia lie has just set in. Figs. 26 and 27 
show two older stages. A further detailed account of the 
growth of the antheridium would be superfluous here. The 
1 Farmer, Annals of Botany, Vol. vi, pp. 265-270, Oct. 1892. 
3 Loc. cit. p. 21. 3 Loc. cit. p. i T'- 
