. A textbook of botany for colleges and universities ... Botany. Figs. 185, matia that fuse with the trichogyne (fig. 185). Perithecia are formed, and the asci bud out from the auxiliary cells (fig. 186), the whole process suggesting the formation of cystocarps among the red algae. # Lichens General character. â With a single ex- ception (p. 91), lichens are Ascomycetes parasitic upon certain algae, the relation between the two organisms being so intimate as to result in a structure resembling a single organism. The dual nature of lichens was announced by Schwendener in 1868, but it was


. A textbook of botany for colleges and universities ... Botany. Figs. 185, matia that fuse with the trichogyne (fig. 185). Perithecia are formed, and the asci bud out from the auxiliary cells (fig. 186), the whole process suggesting the formation of cystocarps among the red algae. # Lichens General character. â With a single ex- ception (p. 91), lichens are Ascomycetes parasitic upon certain algae, the relation between the two organisms being so intimate as to result in a structure resembling a single organism. The dual nature of lichens was announced by Schwendener in 1868, but it was many years before the proof of it be- Siigmjio- came convincing. In i88g Bonnier began myces. i 5, sex organs, ng synthesize lichens; that is, to bring to- branch showing anthendia dis- -' > > a charging spcrmatia; left branch gether "wild algae" and lichen fungi and being a procarp showing tricho- thus produce artificial lichens. The para- gyne (with attached spermatia), ⢠. t ⢠j_i_ ^ ^i i j ^ ''â ^ . ," ... ' sitism is peculiar in that the algae do not carpogonium, and auxihary ^ ° cells; 186, the formation of asci seem to be harmed in most cases, the cells within the peritliecium after being rarely penetrated by the fungus. The fertilization. â AfterThaxter. , j â i- u r i- r algae concerned in hchen formation are tor the most part Cyanophyceae and Protococcales. As would be expected, the algae thrive without the fungus, just as do the wild species; but the lichen fungus soon perishes if it does not come into contact with the appropriate algae. (See p. 91 and fig. 1117.) Body. âThe lichen fungus usually forms a thallus body much more definite and differentiated than do other mycelia, the thallus often re- sembling in form that of certain liverworts. In structure, there is a distinct compact cortical region and a central looser region, in either of which the algae may occur (fig. 190). Two structural types of thallus body are recog- nized,


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Keywords: ., bookcentury1900, bookdecade1910, booksubjectbotany, bookyear1910