420 



BOTANY 



Parmelia). In other cases the spermogonium is at first filled with a hyphal tissue in 

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



from the cells lining the cav- 

 ities. The spermatia. em- 

 bedded in a slimy ma. ai 

 shed from tire spermogoniuni 

 and conjugate with the ad- 

 hesive tip of the tricliogyne 

 (Fig. 372 B). After conjuga- 

 tion the spermatia appear 

 empty and their nucleus has 

 disappeared. When this has 

 taken place the cells of the 

 trichogyne collapse, while tin- 

 cells of the coiled carpogonium 

 swell, undergo divisions. an<i 

 form the ascogonium. From 

 til G Ifi 1 1 * ' r t He isco< r t*n< *u s 



hypha- which bear the asci are 

 FIG. 373. A*apt)/cMa cilmns. Rii>e Bpennogoniwn. Ihe J L 



dark round bodies within the tlmllus an- the xreen Al.ual produced. Ihe vegetative 

 cells, (x 192. After GLffcK.) hyphse composing the fructi- 



fication and the paraphyses 



originate from hyphte which arise below the carpogonium. The fructification may 

 arise from one or from several carpogonia. The behaviour of the sexual nuclei 

 requires further investigation. Such carpogonia have been shown to give rise to 

 the fructifications in a large number of genera. In other genera (Pelliycra, 

 Xo/f rina), 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, 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 nature. 



2. Basidioliehenes (Hymeno- 

 liehenes) ( 01 ) 



The Hymenolichenes are represented 

 by the tropical Cora pavonia, of which 

 the genera Dictyonema and L<ni.tl<itc<t are 

 only specially ditt'erentiated forms. The 

 fungus of this Lichen belongs to the 

 family Thelephoreae (p. 410) ; its flat, 

 lobed,and often imbricated fructifications 

 are also found entirely devoid of Algae. 

 In symbiosis with the unicellular Alga 

 Chroococcus, it forms the fructifications of 

 Cora pavonia (Fig. 374), resembling those of the Thelcphoras with a channelled. 

 basidial hymenium on the under side. Associated symbiotically, on the other 

 hand, with filaments of the blue-green Alga ^'c/' / """"", if the Fungus preponderates, 



FIG. 374.-''c,rv< pavoniu. .1, Viewed f'n>m almve 

 /;. l'i< mi below; hym, hytneniiiin. (Xat. si/e.) 



