278 Evans .— Vegetative Reproduction in Metzger ia. 
cells away from the base. Except for these papillae the gemmae are 
usually destitute of appendages, but in some cases hairs are produced early, 
and even the first ones commonly show a slight displacement to the 
postical surface in the way characteristic for the mature thallus. The 
gemmae just described may be considered typical, but reversions to a more 
embryonic condition are likely to occur in a greater or less degree. Under 
these circumstances a gemma, as fully 
described by Goebel, may be simply 
a cell-row or a cell-layer variable in 
width, and frequently shows no signs 
either of differentiation or dorsiven- 
trality. The germination of a gemma, 
so far as observed, exhibits no features 
of especial interest. It simply gives 
rise to a thallus, which gradually be¬ 
comes wider and more differentiated 
as its growth proceeds, and there is 
no line of demarcation between the 
gemma and the thallus. The pro¬ 
duction of new gemmae on the young 
plant sometimes begins very early, 
especially in the var. idvula . 
Metzgeria quadriseriata , Evans. 
This species is still known from 
a single locality in Japan, Ioki-mura, 
Tosa, where it was collected in 1903 
by Yoshinaga. 1 The gemmiparous 
branches are more slender than normal 
branches, but show no further differ¬ 
ences. The gemmae are usually spar- 
ingly produced and arise without 
definite order. They bear consider¬ 
able resemblance to the gemmae of 
M. furcata , but show no signs of a 
costa and tend to be much narrower. 
Occasionally, they bear a very few short and straight marginal hairs, but 
they are more frequently quite undifferentiated. Although their width, 
through reversion, may be reduced to only one or two cells (Fig. 5, a), 
they are normally from six to eight cells wide. Their length, however, 
varies within wide limits at the time of separation. When a gemma 
germinates the thallus to which it gives rise usually continues narrow and 
1 Cf. Evans: Proc. Wash. Acad. Sci., viii, 142, pi. 6, figs. 1-5, 1906. 
Fig. 5. M. quadriseriata. a. Portion of 
a thallus developed from a gemma; the new 
gemma on the right shows marked indications 
of reversion, x 80. B. Another portion of the 
same thallus, showing dichotomous branching. 
x8o. 
