SECT. IV. 



ASCI. 



301 



observations of M. Tulasne, the true fruit differs little if 

 at all from the asci-bearing fungi. Through the open 

 discs of the higher lichens, sporidia are discharged from 

 perpendicular septate asci which, with their paraphyses, 

 are imbedded in the substance below. The asci are formed 

 by the elongation of some of the cells of that layer into 

 cylindrical septate vessels, generally containing from 

 four to eight sporidia, the ultimate result of as many free 

 cells. In whatever part of a lichen the perithecia may 

 be placed, the asci and paraphyses invariably originate 

 in the medullary layer. 



Fig. 39. a, Panlia perforata, gonidia, paraphysis, and asci ; 6, Calicium tympanellmn, 

 perithecinm and sporidia ; c, Graphis Leprevostei, with, excipulum, asci, and 

 sporidium. 



The thallus or frond of many of these lichens is irre- 

 gularly covered with thick convex scales, in each of 

 which are concealed white or grey bodies, which become 

 flask-shaped, with pores in their extremities. When 

 mature, they exactly resemble the bottle-shaped perithe- 

 cia in the genus Sphseria among fungi. They are lined 

 with branching filaments or other supports, ending in 

 minute ovoid particles, which escape in myriads from the 

 flask-shaped vessels long before the spores appear. They 



