98 
Cavers. — On the Structure and 
and forms a stalked outgrowth. The tuber ultimately becomes detached 
and gives rise to a new plant, but it does not appear to be specially 
adapted for resisting drought, for tubers that have been kept dry (between 
sheets of filter-paper) for even a week were found by the writer to be 
very rarely capable of germination. The tuber bears numerous rhizoids, 
and its cells contain starch-grains ; the superficial cells, except those that 
grow into rhizoids, have their outer walls cuticularized. In several cases 
abundant fungal hyphae were found in the cells of the tuber ; the fungus- 
infested tubers were found to germinate freely, and the hyphae evidently 
belong to the mycorhiza of the thallus. 
Sexual Organs. 
Fegatella is strictly dioecious, and the sexual organs are borne on 
specialized portions of the plant, the receptacles. Each receptacle repre- 
sents a branch of the thallus, or a system of branches. When a resting 
winter-shoot grows out, the four growing-points may either all give rise 
to ordinary broad thallus-lobes, or one of them may produce a sexual 
receptacle. The receptacles are laid down in spring, but the sexual organs 
do not become mature until about the end of June. The earliest stages 
in the development of the sporogonium are observed about the middle 
of July, as a rule, but the spores are not set free until the spring of the 
following year. 
Male Receptacle. 
The antheridial receptacle is sessile, forming an oval cushion studded 
with the openings of numerous cavities, each of which is found, on examin- 
ing sections of the receptacle, to lodge a single antheridium, or sometimes 
two antheridia. Each of these antheridial pores occupies the summit of 
a conical prominence, and between them there occur numerous less con- 
spicuous pores, each opening into an air-chamber (PI. VII, Figs. 1 8, 31). At 
the anterior end of the receptacle are seen the appendages of the ventral 
scales, which curve upwards and backwards in the same manner as in the 
growing-point of a sterile branch. The receptacle is at first bright green 
in colour, but later the walls of the antheridial cavities, together with the 
prominences just mentioned, assume a deep red or purple colouration. The 
examination of serial sections through receptacles of different ages shows 
that the apex of the male branch undergoes repeated forking, so that 
several (usually from six to eight) growing-points are formed. Each of 
the latter then gives rise to a zig-zag row of antheridia, the oldest being 
found at the centre of the receptacle and the youngest at the margin 
(PI. VII, Figs. *9-31). 
