18 PROCEEDINGS OF THE AMERICAN ACADEMY 



lichen-spores in the presence of Cystococcus freed from another 

 species of lichen, and for Alfred Mciller by the successful culture 

 of lichen-spores alone in a nutritive fluid, to settle the whole matter 

 conclusively as far as the species cultivated were concerned. Miiller's 

 cultures, the preliminary results of which were puhlished in 1887,* 

 included fifteen species, representing ten genera of crustaceous lichens, 

 and established the following jioiuts : " From a lichen-spore a fully 

 differentiated thallus can be grown, the development of which can be 

 followed on a glass slide without the use of an opaque substratum. 

 Gonidia never appear in such a thallus provided that the culture- 

 method employed secures complete isolation. Experiments on the 

 germination of lichen-spermatia led to like results. A large number 

 of spermatia germinated like other conidia, the resulting mycelium and 

 thalline body could not be distinguished from those developed from 

 an ascospore of the corresponding lichen, and, like it, developed new 

 spermogonia whose spermatia corresponded to those originally sown." 



Finally, the discussion on these lines was concluded by the results, 

 published in 1889,t of Bonnier's careful synthetic cultures, extending 

 over a continuous period of three years, during which time, by spore 

 cultures of a large number of heteromeric lichens in the presence of 

 algae procured from pure cultures of previously determined algae, he 

 produced a number of typical, and in some cases fruiting lichens. The 

 reader's attention, however, must be drawn to the fact that as yet we 

 have heard nothing from Moller on the subject of the bomoeomeric 

 lichens, and that Bonnier was unsuccessful in his experiments upon 

 Collema and Ephebe. 



Meanwhile, as botanists became convinced that Schwendener's first 

 hypothesis with regard to the parasitic nature of the lit-hen fungus 

 was an indisputable fact, attention came to be directed to other kin- 

 dred topics of no less interest and importance. If it had not been 

 definitely stated, it was at least tacitly assumed by most of the earlier 

 mycologists, tliat lichens were sexual in their method of reproduction, 

 and that the spermatia were the male organs. But we have seen that 

 from these very spermatia Moller professes to have grown fully de- 

 veloped thalli, without the intervention of any female organ. If this 

 is so, it is a fact which must militate very strongly against the view 

 that the fruit of the corresponding lichens is in any respect sexual in 



* Moller, " Ueber die Cultur Flechtenbildenen Ascomyceten ohne Algen," 

 1887. 



t Bonnier, Annales des Sciences Natnrelles, Ser. VII. Tom. IX., 1889. 

 Revue generale de Botanique, I., 1889. 



