Fink: Classification of Lichens 
105 
apparent enough between Thelophora and Cora-like lichens, 
where we have the process of the evolution of new lichen- phyla 
going on before our eyes, and also in the relationship of Graphis 
to Hysterium, Calicium to Mycocalicium, Bilimbia to Mycobilim- 
bia, Basidia to Mycobacidia, Lecidea to Patinella, etc. It may 
be added here that the recent papers by Acton ( i), Lagerheim (79), 
Schneider (114), de Seynes (122, 123), Zukal (151) and others 
add to the evidence through the discovery of many lichens in the 
making. These researches are considered at length below. 
The arguments of those who believe that lichens are fungi seem 
perfectly tenable, but close analysis is necessary. For the writer 
at least, it matters not whether the relation of the lichen to the 
alga is parasitism, saprophytism, or mutualism, even of the type 
that is believed by some botanists to be the acme of individualism, 
for it seems reasonable to him to regard the lichen a fungus if 
the relation is the most mutual possible as well as if it is an- 
tagonistic. But the problem arises whether it is consistent to 
regard the lichen a fungus, since in so doing we are ignoring 
part of that which was originally considered a portion of the 
lichen, viz., the symbiotic alga. The zoologists do not regard 
zodchlorellae a part of Hydra viridis, fresh water sponges, or 
other animals in which they occur. Though the symbiotic rela- 
tion of the lichen to the alga is different from that of the hydra 
or the sponge to the alga found within it, and though the alga 
may sometimes form a larger portion of the symbiotic colony 
than does the lichen, congruity demands excluding the alga from 
our conception of the lichen. 
It has been suggested that the term lichen should be given over 
to plant physiologists and ecologists, to signify a colony of special 
interest to them. There are at least two difficulties with this 
proposition. The first is that most botanists will continue to use 
the term lichen for purposes of taxonomy and morphology, in 
spite of any suggestions that might be made, and the second is 
that relegating the term to workers in certain fields of botanical 
work would not be the best solution, were it feasible. After 
studying the literature of lichen physiology and ecology carefully, 
it does not appear best for physiologists and ecologists to depart 
from the usual method and consider colonies rather than individ- 
