APOGAMOUS REPRODUCTION 175 



also by him the primordium arises among the cells of the periderm on which 

 the lichen grows, and he failed to find any trace of a sexual act. In his 

 elaborate study of Gloeolichens Forssell 1 established the presence of carpo- 

 gonia with trichogynes in two species Pyrenopsis phaeococca and P. impolita, 

 but without any appearance of fertilization; in all the others examined, the 

 origin of the fruit was vegetative. Wainio 2 records a similar observation in 

 a species of Pyrenopsis in which there was formed a spiral ascogonium and 

 a trichogyne, but the latter never reached the surface. 



Neubner 3 claimed to have proved a vegetative origin for the asci in the 

 Caliciaceae; but he overlooked the presence of spermogonia and his conclu- 

 sions are doubtful. 



Fiinfstuck 4 found apogamous development \.\\Peltigera(mc\udingPeltidea) 

 and his results have never been disputed. The ascogonial cells are surrounded 

 at an early stage by a weft of vegetative hyphae. No trichogynes are formed 

 and spermogonia are absent or very rare in the genus, though pycnidia with 

 macrospores occur occasionally. 



Some recent work by Darbishire 5 on the genus supplies additional details. 

 The apothecial primordium always originated near the growing margin of 

 the thallus, where certain medullary hyphae were seen to swell up and stain 

 more deeply than others. These at first were uninucleate, but the nuclei 

 increased by division as the cells became larger, and in time there was 

 formed a mass of closely interwoven cells full of cytoplasm. " No coiled 

 carpogonia can be made out, but these darkly stained cells form part of a 

 connected system of branching hyphae coming from the medulla further 

 back." Long unbranched multiseptate hyphae evidently functionless tri- 

 chogynes travelled towards the cortex but gradually died off. Certain of 

 the larger cells the "ascogonia" grew out as ascogenous hyphae into 

 which the nuclei passed in pairs and finally gave rise to the asci. 



These results tally well with those obtained by M. and Mme Moreau 6 , 

 though they make no mention of any trichogyne. They found that the 

 terminal cells of the ascogenous hyphae were transformed into asci, and the 

 two nuclei in these cells fused the only fusion that took place. In Nephro- 

 mtum, one of the same family, the case for apogamy is not so clear; but 

 Fiinfstuck found no trichogynes, and though spermogonia were present on 

 the thallus, they were always somewhat imperfectly developed. 



Sturgis 7 supplemented these results in his study of other lichens con- 

 taining blue-green algae. In species of Heppia, Pannaria, Hydrothyria, 

 Stictina and Ricasolia, he failed to find any evidence of fertilization by 

 spermatia. 



Solorina, also a member of Peltigeraceae, was added to the list of 



1 Forssell 1885. 2 Wainio 1890, p. x. 3 Neubner 1893. 4 Fiinfstuck 1884. 



5 Darbishire 1913. 6 Moreau 1915. 7 Sturgis 1890. 



