Sexual Reproduction in Pyronema confluens 
and the Morphology of the Ascocarp. 
BY 
ROBERT A. HARPER, 
Professor of Botany in the University of Wisconsin, 
With Plates XIX— XXI. 
Introduction. 
HE very interesting researches of Stahl (32) on the 
jL sexuality of the Collemaceae have received full con¬ 
firmation from a number of sources, and the doctrine that 
a type of fertilization similar to that in the red Algae is to be 
found very generally among the Lichens must be regarded as 
well established. The nuclear phenomena involved in the 
fertilization have in no case as yet been worked out, nor is 
the account of the cell-fusions complete and consistent, still 
the existence of trichogyne, archicarp and spermogonium, and 
their interpretation as functional sexual organs can hardly be 
doubted, in view of the mass of evidence that has been 
gradually accumulated. 
Krabbe’s work on Cladonia , Baeomyces , and Sphyridium 
indicates that these forms may possibly be without sexual 
organs. Krabbe (20) investigated Cladonia very carefully, 
and claims that in this genus the ascogenous hyphae are part 
of the same system of branches from which the paraphyses 
arise. He notes, that the ascogenous hyphae arise only at 
one period in the development of a podetium, and that after 
a certain number have been formed simultaneously, no more 
new ones arise except by the branching of those already 
[Annals of Botany, Vol. XIV. No. LV. September, 1900.] 
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