ASCOLICHENES. 



139 



This theory regarding the symbiosis of Fungi and Algae to form a Licheii is 

 termed the Schwendenerian theory, after the first scientist who advanced it with 

 any weight. It had heen already indicated by De Bary, and further arguments 

 in its support have at a later time been adduced by Bornet, Stahl, Treub, 

 Frank, Bonnier, Alfr. Holier and others. 



FIG. 131. Nostoc liclienoides, which is attached 

 by a germinating thread (?i) of Colletua glaucescens. 



FIG. 133. Ephele pubcfccns. 

 The apex of a branch of the 

 thallus with two lateral branches 

 (*) : h its hypha?;! g the apical 

 gonidinrn of the main branch. 



FIG. 135. A Germinating spore of Physcia parie~ 

 tina with Protococcus viiidis. B Synalissa eymphorea 

 with Glaocupsa. C Cladonia furcata with Proto- 

 coccus. 



The thallus of the Lichen appears mainly under three forms : 



1. The CRUSTACEOUS, which adheres firmly to the substratum 



(bark, stone) throughout its entire surface, without being raised 



into any free patches or lobes. It has, in many instances, no 



definite outline, and hyphal-branches from it often penetrate 



