130 
F. Cavers. 
two opposite marginal notches, whilst the others are spherical and 
much smaller. Each gemma is borne on a slender unicellular 
stalk, and between them there grows out numerous mucilage-hairs. 
The spherical gemmae differ further from the lenticular ones in the 
fact that they usually begin to germinate and to produce young 
plants before being set free. This gemination in situ is sometimes 
observed in the case of Blasia, the gemmae of which may put out 
rhizoids before leaving the receptacle. It is interesting to note 
that the archegonia in Cavicularia are produced in receptacles 
exactly similar to those containing gemmae. 
III. ylingermanniales. B. Jungermanniaceae Acrogynae. In 
this group, which includes the vast majority of the species of 
Hepaticae, asexual reproduction takes place by means of caducous 
shoots (normal or adventive in origin) and gemmae, these two main 
types being connected by transitional organs 
Caducous branches. By the dying away of the older parts of 
the shoot, the branches become separated and grow independently. 
This simple process of multiplication is of extremely common, 
perhaps universal, occurrence in the Acrogynae. The branches 
thus separated may either be those formed in the ordinary manner 
at the apical growing-point or adventive branches of relatively late 
origin. The adventive branches appear invariably to arise from 
the ventral surface of the stem, and in species provided with ven¬ 
tral scales (amphigastria) each of these branches usually appears 
in the axil of a ventral leaf. In most cases, these ventral branches 
are at least partially derived from the inner cells of the stem. The 
growing-point of the branch is laid down immediately behind that 
of the stem itself, but instead of at once growing out, as the 
ordinary lateral branches do, it remains dormant for a considerable 
time. The apical cell of the ventral branch becomes covered by a 
superficial layer of cells, forming a sheath through which the 
resting-branch breaks when the apical cell resumes its growth. In 
some genera, e.g., Lophocolea , Cephalozia, Kantia, nearly all the 
branches are of this intercalary type and spring from the ventral 
surface of the stem, normal lateral branches being very seldom 
formed. The slender small leaved shoots (“flagella ”) of Bazzania 
may be cited as further examples of the same type of branching. 
In cases where the growth of the main stem is arrested by the 
formation of archegonia, it is very common to find one or more 
branches arising immediately below the involucre or perianth. 
These “ innovation-shoots,” like the intercalary ventral branches, 
