No. 400.] FUNGUS AND ALGA IN LICHENS. 247 
different genus. Assuming that Hedlund’s experiments weré 
conducted with sufficient cleanliness to prevent Protococcus 
from replacing Gloeocapsa, this return from Gloeocapsa-like 
characters to the original Protococcus characters is interesting 
evidence of the influence of living competitors (other algae) and 
enemies (fungi), as well as of lifeless forces (light, food, etc.), 
upon the appearance of living organisms. Since small alga 
are so modified, both inside and outside of the lichen body, by 
external influences, their identification and the identification of 
gonidia become in some instances matters of difficulty, in which 
experiment must play an important part. 
As to the fungus-like component of lichens, all are now agreed 
that the hyphze are fungus, but the identity of any fungus com- 
ponent of lichens with species of fungi living otherwise is diffi- 
cult to prove and is absolutely denied by many. According to 
Reinke,! the fungus components of the lichens of to-day came: 
from fungi no longer existing as distinct species. That this 
is necessarily true it is impossible to see; that it is true is hard 
to believe, for, as has been shown above for the gonidia, the 
other organisms with which it is associated, as well as the life- 
less forces to which it is subjected, may so influence an organism 
that its appearance and behavior will be profoundly modified. 
Although Moller’s? now classical experiments in cultivating the 
fungus components of certain simple lichens on artificial media 
were successful as far as they went, they did not go so far as 
to show that the fungus could reproduce itself by ascospores 
formed in normal apothecia, and, after all, only lichens of simple 
thallus form were cultivated at all. It is only natural, but also 
greatly to be regretted, that the extremely slow growth of li- 
chens and of their fungus components has deterred most bota- 
nists from experimenting on these interesting plants. Reinke’s 
view can be proved or disproved only by successful culture of 
1 Reinke, J. Abhandlungen über Flechten, III. /ahré. f. Wiss. Bot., Bd. xxviii 
(1895), p. 64: Kein Flechtenpilz ist bisher im freilebenden Zustande beobachtet 
worden — abgesehen von den Basidiolichenen — und es hat demnach den An- 
Schein, dass alle Pilze, aus denen sich Flechten entwickelt haben, als Pilze zu 
Grunde gegangen sind. 
? Móller, A. Ueber die Cultur flechtenbildender Ascomyceter ohne Algen. 
Jnaug. Diss. Münster, 1887. 
