472 



BOTANY 



PART II 



structure in the different species. In some cases the podetia are stalked and 

 funnel-shaped, bearing on the margin or on outgrowths from it knob-like apothecia, 

 which in C. pyxidata are brown, in C. coccifera (Fig. 427) bright red. In other 



FIG. 424. Usnea barbata. ap, Apothecium. 

 (Nat. size.) 



FIG. 425.Cetraria islandica. ap, Apothecium. 

 (Nat. size.) OFFICIAL. 



species the erect podetia are slender and cylindrical, simple or forked ; in C. rangi- 

 ferina, Reindeer Moss, which has a world-wide distribution, particularly in the 

 tundras of the North, the podetia are finely branched (Fig. 428), and bear the smal 



brown apothecia at the ends of the branches. 

 The primary thallus of this species soon dis- 

 appears. 



The ascus fructifications (apothecia or 

 perithecia) of the Lichens originate, as 

 STAHL and, more recently, BAUR ( 89 ) have 

 shown, from carpogonia or female sexual 

 organs which are frequently present in 

 large numbers on young lobes of the thallus. 

 The carpogonium (Fig. 429) is here a multi- 

 cellular filament, the lower part of which 

 is spirally coiled, while it continues above 

 into a trichogyne composed of elongated 

 cells and projecting from the surface of 

 the thallus. All the cells are uninucleate 

 and communicate with one another by 

 means of pits. Those of the 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. 430) are presum- 

 ably the male sexual cells. The spermatia develop in different ways ( 90 ). 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 hypha] tissue in which 



FIG 



426. Parmelia acetabulum ; grows on 

 trees. (After REINKE.) 



