82 



MANUAL OF BOTANY 



legniee, the actual process does not take place. It is, however, 

 convenient to describe these structures as sexual, while reserving 

 the question of actual fusion of the gametes. 



The group derives its name from the fact that whether pro- 

 duced after sexual fusion, or parthenogenetically, the spores 

 arise in closed cells known as asci. There is much variety in 

 the mode of origination of the latter, but they agree in that there 



Fig. 836. 



Fig. 835. Section of upper portion 

 of thallus of a lichen, showing 

 archicarps. a, h. Trichogynes. 

 e, /. Coiled basal portion of 

 archicarps. c. Nostoc filaments. 

 (/. Fungal hyphfe. After Kny. 



Fig. 836. Section of spermo- 



gonium of a lichen, a. Hyphae of 

 the thallus. b. Algal cells, c 



Sterigmata. Fig. 837. Highly 



magnified fragment from the 

 wall of a spermogonium of Par- 

 melin parietina. sp. Articulated 

 sterigmata or spermatophores. 

 s. Spermatia. gon. Algal cells. 



is no case of a differentiated female gamete giving rise to them. 

 The fungi of this group in this respect resemble the Ehodo- 

 phyceae of the group of Algae. 



The sexual organs show a great deal of difference in degree 

 of complexity. The female organ is usuall^^ an arcliicav}) 

 consisting of a coiled portion, known as a carjpogonium, with 

 sometimes an elongated part, called a triclwgyne {fig. 835). In 



