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LICHEN ASCI AND SPORES 191
usually more or less collapsed. The component parts of the apothecium
were entirely normal and healthy, but the paraphyses and the few asci were
crushed aside by the intrusion of numerous slender unbranched septate
conidiophores. Several of these might spring from one base and the hypha
from which they originated could be traced some distance into the ascogenous
layer, though a connection with that cell-system could not be demonstrated.
While still embedded in the hymenium, an ellipsoid or obovate swelling
began to form at the apex of the conidiophore; it became separated from
the stalk by a septum and later divided into a two-celled conidium.
The conidiophore increased in length by intercalary growth and finally
emerged above the disc; the mature conidium was pyriform and measured
1 5-20 /z, x 9-11 yu,
Steiner regarded these conidia as entirely abnormal; pycnidia with
stylospores are unknown in the genus and they were not, he alleges, the
product of any parasitic growth.
b. COMPARISON WITH HYPHOMYCETES. The conidial form of fructi-
fication in fungi, known as a Hyphomycete, is generally a stage in the life-
cycle of some Ascomycete; it represents the rapid summer form of asexual
reproduction. The ascospore of the resting fruit-form in many species germinates
on any suitable matrix and may at once produce conidiophores and
conidia, which in turn germinate, and either continue the conidial generation
or proceed to the formation of the perfect fruiting form with asci and asco-
spores.
Such a form of transient reproduction is almost impossible in lichens, as
the hypna produced by the germinating lichen ascospore has little vitality
without the algal symbiont. In natural conditions development practically
ceases in the absence of symbiosis. When union between the symbionts
takes place, and growth becomes active, thallus construction at once com-
mences. But in certain conditions of shade and moisture, only the rudiments
of a lichen thallus are formed, known as a leprose or sorediose condition.
Soredia also arise in the normal life of many lichens. As the individual
granules or soredia may each give rise to a complete lichen plant, they may
well be considered as replacing the lost conidial fructification.
C. CAMPYLIDIUM AND ORTHIDIUM
Mu'ller 1 has described under the name Campy lidium a supposed new type
of asexual fructification which he found on the thallus of tropical species of
Gyalecta, Lofadium, etc., and which he considered analogous to pycnidia and
spermogonia. Wainio 2 has however recognized the cup-like structure as a
fungus, CypJiella aeruginascens Karst, which grows on the bark of trees and
occasionally is parasitic on the crustaceous thallus of lichens. Wainio has
1 Miiller 1881.
2 Wainio 1890, n. p. 27.