Fink: Classification of Lichens 
121 
killed, the lichen producing conidia but neither spermagonia nor 
ascospores. But when the attack comes later, it takes longer to 
kill the alga, and the lichen produces spermatia and ascospores. 
Finally, some of the algae run their whole life history without 
being attacked by the lichen. 
Nylander (97) held that he found lichens most abundant where 
algae are absent; but he doubtless based his statement on an 
erroneous impression and not on careful observation. Peirce 
(98) finds commonly on old fences free algal cells, others in- 
vested by hyphae and so on up to mature lichens of various species 
common in his region. Williams (141) observed that lichens 
appear first in damp places, where algae are most numerous, and 
spread gradually from these to other locations. He found that 
they grow first on the shady and moist parts of trees and fences 
and rarely if ever appear first on dry, wind-exposed portions. 
These observations of Peirce and Williams agree in general with 
what the writer has noted many times, though there is no doubt 
that lichens will grow in very dry places. 
We have many times found the algal clusters which proved to 
be parasitized by fungal hyphae, growing both in the vicinity of 
lichens and in other moist places, but have not been disposed to 
agree with Schneider that these are necessarily the primordia of 
very primitive lichens. It has seemed more reasonable to sup- 
pose that they may be young conditions of higher as well as of 
lower lichens which are present in mature form near by. Years 
of observation of the development of these primordia should give 
valuable results, whether growing in the vicinity of lichens or 
elsewhere. * 
Nylander (94) mentioned algae occurring in the hymenia of 
pyrenomycetous lichens. Fuisting (62) found that in Stigma- 
t omnia cataleptum (Ach.) Koerb. the hymenial algae are certain 
algal host cells, which become imprisoned in primordia of 
apothecia and multiply as the apothecium develops. Winter ( 143) 
agreed in general with Nylander and Fuisting, all three finding 
that the hymenial algae are smaller than other algal host cells; 
but Winter noted in addition the paler color of the former. 
These hymenial algae occur in early stages of development, or in 
