Biology of Fegatella conica. 107 
of all previous authors who have made a special study of this organ in 
the Hepaticae (Kny, Strasburger, Janczewski, Campbell). Gayet states 
that in all the Hepaticae examined by him, the cover-cell of the young 
archegonium acts as an apical cell, at any rate for some time, segments 
being cut off from it which contribute to the growth in length of the 
neck. Gayet’s main conclusion is that both in Hepaticae and in Mosses 
the neck-cells are, at any rate to a large extent, derived from the segmenta- 
tion of an apical cell (the cover-cell), and that in both groups the neck- 
canal-cells arise by division of the primary canal-cell — in short, that there 
is no essential difference in the development of the female organ in the 
two groups, such as has been generally held to exist. The Marchantiaceous 
forms studied by Gayet were Targionia , Preissia , and Marchantia. Owing 
to the fact that the archegonia of Preissia and Marchantia are developed 
in large numbers in each group, it is much easier to obtain a good series 
of stages than in the case of Fegatella , where each receptacle shows only 
seven or eight archegonia altogether. The result of the writer’s observa- 
tions on Preissia commutata and Marchantia polymorpha , using stained 
serial microtome- sections, has been to entirely confirm the accounts given 
by Strasburger, Janczewski, and Campbell for these and other Marchanti- 
aceae. Gayet’s figures are not convincing, and his methods of preparation 
are, as has been pointed out by Campbell (1898), quite inadequate for the 
exact determination of the points in question, for unless recourse be had 
to modern methods of fixation, paraffin-embedding, and serial sectioning 
by microtome, it is almost impossible to make out the precise sequence 
of nuclear and cell divisions in a developing organ which consists of a solid 
aggregate of cells. 
The tissue of the receptacle, above and between the archegonia, contains 
numerous air-chambers, separated by thin partitions, consisting mostly of 
a single layer of cells (Figs. 30, 31) ; here and there we find large mucilage- 
containing cells, both in the compact tissue and in the walls of the chambers. 
The pores are of the compound or barrel-like type ; the cells forming the 
upper tiers are narrow, whilst the lower tiers, projecting into the chamber 
are broader, the lowest cells being nearly spherical in cross-section. If 
sections of a fresh receptacle be examined in water, it is found that the 
cells- of this lowest ring are so arranged as to leave a wide opening into the 
underlying air-chamber ; but on irrigating the section with a five per cent. 
KN 0 3 solution, these cells become flaccid and the opening becomes very 
much smaller, or the pore may become completely closed, the cells of this 
ring coming into contact with each other. On adding water, the cells 
resume their former state of turgescence and the pore again becomes open. 
It appears from this experiment that the lowest tiers of cells surrounding 
these barrel-shaped pores act in the same way as the guard-cells in the 
stomata of higher plants, and have the function of regulating the opening 
