FUNGI. — LICHENS. 



125 



8. Palmellaceae Many fruticose and foliaceous Lichens. 



Cystocoaus Iiuniitola . . Fhyscia, Cladonia, Evernia, Us/ica, Bryopogo/i, 

 Anaptychia. 



Pleiirococcus Eiidocarfion and various crustaceous Lichens. 



g. Coleochaeteae {PhyUactidiuni ' ). OpegrapJia Jilicina. 



The influence of the hyphae of the Fungus on the gonidia has been aheady aUuded 

 to in the description of the hymenial gonidia. This influence is different in different 

 species. It is often scarcely perceptible, especially if the gonidia are unicellular 

 Algae, but very striking sometimes and especially in the case of filamentous Algae, 

 using that term in the widesi sense. The filaments become crooked, divide into short 

 pieces, or separate into single cells, as in Opegrapha varia, the gonidia of which 

 belong to the filamentous Alga Chroolcpus. At the margin of the thallus there are 



Fig. 84. Examples nf various .\lg-ae which are 1 

 hypha of the Fungus, g the gonidiuni. A germinating 

 closely to Protococcus viridis. B a filament of Scytonci) 

 C froni the thallus of the Lichen P/iysvia chataganuni 

 (gonidiumj. D from the thallus of the Lichen Synaiissa 



iiployed as the gonidia of Lichens, h indi 

 pore s of Physcia payietuta. the ge 



Iw.iys th< 



be of which adheres 

 « ith hyphae of Stereocautojt yatnulosits twined round it. 

 a hyphal branch is entering a cell of the nostoc filantent 

 •))iphorea ; the gonidia are the Alga Gloeocapsa. E from 



the thallus of the Lichen Cladonia furcata ; the gonidia which 

 tococcus. After Bornet. .-/, C, Z?, E magn. 950, B 650 times. 





iided by the hyph; 



; the cells of Pr 



perfect filaments of Chroohptis still to be seen ; but as they become surrounded by the 

 hyphae they break up into short pieces or into single cells. On the other hand, we find 

 in old specimens of Op. varia that the gonidia have reassumed their normal appearance ; 

 they elongate, form straight filaments, and produce the zoosporangia of the algal genus 

 Chroolepus. The gelatinous investment possessed by many Algae which serve as 

 Lichen-gonidia disappears in the Lichen-thallus. Among the most remarkable are 

 the cases where the branches of the hyphae penetrate into the gonidia, as in Arnoldia 

 and Physma (Fig. 84); this gave occasion to the old and erroneous notion that gonidia 



' The systematic position of this Alga is still uncertain owing to our itjnorancc of its oignns of 

 reproduction ; the vegetative state however resembles Cokoihactc, and like it forms broad disks 

 on le.ives and other objects. 



