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 



I 5-20 /i X 9-1 I fi. 



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. 



d. 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 ger- 

 minates 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 hypha 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 



Miiller' has described under the name Campylidium a supposed new type 

 of asexual fructification which he found on the thallus of tropical species of 

 Gyalecia, Lopadium, etc., and which he considered analogous to pycnidia and 

 spermogonia. Wainio^ has however recognized the cup-like structure as a 

 fungus, Cyphella aeruginascens Karst., which grows on the bark of trees and 

 occasionally is parasitic on the crustaceous thallus of lichens. Wainio has 



1 MuUer 1881. " Wainio 1890, n. p. 27. 



