350 The Botanical Gazette. [September, 
The hepatics possess almost absolutely no utilitarian aspect. 
Beyond the doubtful use of one or two in medicine, and the 
occasional occurrence of one or more tropical species as weeds, 
they are, so far as the physical condition of the human race 
is concerned, an entirely useless group of plants. Theydo — 
not trouble the experiment station botanist, the horticulturist 
finds no use for them, and the general public does not see 
sufficient importance in them to subscribe a single shilling 
for the endowment of a laboratory for research in such an 
apparently barren field. And yet from the higher stand- 
point of genetic relationship, there is probably no single group 
of plants that occupies such an unique position in the plant 
world. What the comprehensive and heterogeneous group 
‘‘Vermes” is to the animal kingdom, the Hepatice are 
plants, with this difference, that we have here a much less 
complicated group of organisms with which to deal. _ 
To understand more fully the relation of the Hepatice to 
the evolution of the green plants and particularly to their role 
in the development of the alternation of phases of bia : 
tion which has attained such extended proportions de = 
ferns and other pteridophytes, it is desirable to bring in vias | 
review the successive stages in the processes of mae : 
from the simplest forms upward. For it must be remem 
that even if the methods of reproduction cannot serve as - 
means of separating the primary types of the thallon a 
in a natural system of classification, they nevertheless a : 
sent the highest function that is manifested in organi” ” 
The successive stages may be characterized as follows: 
con- 
I. Among forms whose only method o ; 
< 
” 
division 
Among forms in which conjugation occurs . 
successive stages of distinct sexual reproduction ne tT 
fore the idea of bisexuality has been different “increase 
purposes seem involved in this process, (1) partes and 
vitality by the union of elements of separate oe ey 
the production of a structure capable of holding V oe 
