42 HUMPHREY 
tubes of more than usual length while some showed the forma- 
tion of cross-walls very early. The young plants in the nutri- 
ent solution have grown rapidly, producing in some instances 
as advanced a development as is seen in Fig. 21, within eigh- 
teen days. A very few young plants in which there was only 
a slight germ-tube development had already begun to assume 
the dorsi-ventral form common to this genus. Desiccated 
plants of Azmbrzaria, Reiccia and Fossombronia when placed 
in Knop’s solution revived quickly producing within a few 
days a greatly increased number of rhizoids and in the case of 
Fossombronta, many more than the usual number of antheridia, 
closely covering the dorsal surface of the young growing shoot. 
From these and other results it seems highly probable that 
Knop’s nutrient solution exerts a stimulative influence upon the 
development of the thallus, rhizoids, and reproductive organs 
as well as the germination of the spores. Further investigation, 
however, with solutions of varying strength and composition is 
needed in order definitely to determine the nature and chemical 
composition of the salt or combination of salts that act as a 
. stimulus to growth. 
According to Goebel,’ germination in the Marchantiez when 
compared with other thallose liverworts presents certain char- 
acteristic differences. He separates the product of germina- 
tion of a spore of Prezssza for example, into three structures, 
z. €., the germ-tube, the ‘‘ pro-embryo” and the young plant. 
He finds that the ‘* pro-embryo” is positively heliotropic and 
develops at its end a flattened cell mass which he terms the 
germ disk. This forms at right angles to the direction of the 
light-rays and the young plant arises from one quadrant of the 
germ disk as shown in his Fig. 95. 
On the same page he states that a similar germination is 
common in the Ricciez contrary to the description and figures 
of Campbell? who studied the germination of /tzccza trichocarpa 
and a number of other forms. He refers to Campbell’s Fig. 9, 
p. 38, as failing to bear out his statement that the axis of growth 
in the young plant is continuous with that of the germ-tube. 
AL OG. Ctl, Pak It. 
CICOENGIt. TStrede, (p..39% 2died., 9. 8o. 
v bet 
