SECT. I 



CRYPTOGAMS 



421 



the cells are uninucleate and communicate witli one another by means of pits. 

 Tliose of tlie lower part of the filament contain abundant protoplasm. Apart from 

 their multicellular nature these structures recall the carpogonia found in the 

 Florideae. The spermatia which originate in spermogonia (Fig. 361) are presum- 

 ably the male sexual cells. The spermatia develop in different ways (^^). In some 

 cases the inner wall of the spermogonium is lined with simple or branched hyphal 

 branches from the ends of which the spermatia are abstricted {Peltigera, Parmelia). 

 In other cases the spermogonium is at first filled with a hyx)hal tissue in which 

 cavities are formed later and the spermatia arise on very small and thin stalks from 

 the cells lining the cavities (AnaptycMa, Physcia, Stida). The spermatia, 

 embedded in a slimy mass, are shed from the spermogonium and conjugate with 

 the adliesive tip of the trichogyne (Fig. 360, B). After conjugation the 

 spermatia appear empty and their nucleus has disappeared. When this has 

 taken place the cells of the trichogyne collapse, while the cells of the coiled carpo- 

 gonium swell, undergo divisions, and form the ascogonium. From the latter the 

 ascogenous hyphae which bear the asci are produced. The vegetative hyphae 

 composing the fructification and the paraphyses originate from hyphae which arise 

 below the carpogonium. The fructification may arise from one or from several 

 carpogonia. Tlie behaviour of the sexual nuclei requires further investigation. 

 Such carpogonia have been sliown to give rise to the fructifications in a large 

 number of genera. In other genera {PeUigera, Solcrina) they are reduced and the 

 trichogyne is wanting, and the reproduction is apogamous. Spermogonia are as a 

 rule not found in these cases, or are, as in the case of Nephromium, clearly 

 degenerating structures. It has been shown by A. Moller (^^) that the spermatia 

 of Lichens can germinate and produce a mycelium ; but this is not inconsistent 

 with their primitively sexual natirre. 



2. Basidiolichenes (Hymenoliehenes) Q-'^^) 



The Hymenoliehenes are represented by Corapavonia, of which the genera Diciy- 

 onema and Laudatea are only special growth forms. This Lichen is widely spread 

 in the tropics growing on the soil or on 

 trees. The fungus of this Lichen belongs 

 to the family Thelephoreae (p. 411) ; its 

 flat, lobed, and often imbricated fructifica- 

 tions are also found entirely devoid of 

 Algae. In symbiosis with the unicel- 

 lular Alga Chroococcus, it forms the 

 fructifications of Coraptavonia (Fig. 362), 

 resembling those of the Thelephoras 

 with a channelled, basidial hymenium 

 on the under side. Associated sym- 

 biotically, on the other hand, with fila- 

 ments of the blue-green Alga Scytoncma, 

 if the Fungus preponderates, it produces 

 the bracket-like Lichens of the Dictyo- 

 nema form, found projecting from the 

 branches of trees with a semicircular 

 or nearly circular thallus, having the 

 hymenium on tlie under side. ' tVhen 

 the shape of the thallus is determined by the Alga, a Lichen of the Laudatea 



Fio. 362. — Cora -pavonia. A, viewed from above; 

 B, from below ; liym, liymenium. (Xat. size.) 



