The President's Address. By Dr. R. Braithwaite. 143 
they are crowded into a coma or head. The leaves are always nerve- 
less, and composed of two very different kinds of cells — one large, 
vesicular, and hyaline, of a flexuose form, usually containing spiral 
fibres attached to the internal surface, and having circular perforations 
in their walls; the other enclosed between these are very narrow, 
coloured or chlorophvllose cells, the form and relation of which is 
best seen by a transverse section. The male inflorescence is on the 
upper branches, on which the bracts are closely imbricated, and often 
coloured purple or yellow ; and the antheridia are stalked, globose, 
and stand singly by the side of each bract. The archegonia are like 
those of the mosses, and after impregnation the capsule is elevated 
on the end of a long naked branch ; the sporogone is globose, with 
a flat lid, and always without a trace of peristome. Inhabiting 
moorland bogs, there is great uniformity in the appearance of these 
plants, and there is great difficulty in deciding what is of specific 
value, and what is due to change in local conditions. The present 
tendency seems to be multiplication of species on rather slight 
grounds, with numerous sub-species, varieties, and forms. 
The Hepaticm, or Liver-mosses, stand lower in the scale than 
those we have been considering, as is evident by a number of species 
never passing beyond the thallose stage of development, e. g. Mar- 
chantia, Riceia, Lunularia, Grimaldia, &c., all differing widely from 
each other in the form of fruit, but having one organ in common 
with the leafy forms, namely, the presence of elaters or spiral threads 
with the spores. 
These leafy and branched species represented by the Junger- 
manniacem constitute the bulk of the order, and many at first sight 
may readily be mistaken for mosses, but the capsule is totally different, 
having no operculum or peristome, but simply splitting into four 
valves, and soon passing into decay. The leaves also differ widely 
from those of the mosses, being very frequently lobed or cut into 
segments, or having curious little pouches attached; their arrange- 
ment is usually bifarious, and there is generally present a series of 
under-leaves or amphigastria, which differ considerably from the 
lateral leaves, both in form and size ; the plants have thus in most 
cases a dorsal and ventral aspect. The elaters are very interesting 
objects for the Microscope, consisting of a long fusiform cell with 
thin hyaline walls, and on the interior of which run one to three 
spiral bands. 
Until recently the Hepaticae have been much neglected, and I 
would point out to some of our botanical friends in want of a hobby 
— and I like men with hobbies — that they will be well rewarded by 
taking up the study of these interesting plants, as they offer a field 
for new discoveries which is certainly rich, and one which will prove 
certainly attractive. 
Of the ten thousand or more species of the Bryophyta, not one 
can be studied without the Microscope, and even with its aid the 
