viii CONTENTS 



II. LICHEN HYPHAE 



PAGE 



A. Origin of Hyphae 46 



B. Development of lichenoid Hyphae ... 47 



C. Culture of Hyphae without Gonidia . 49 



D. Continuity of Protoplasm in Hyphal Cklls 51 



III. LICHEN ALGAE 



A. Types OF Algae 51 



a. Myxophyceae associated with Phycolichens 



b. Chlorophyceae associated with Archilichens 



B. Changes induced in the Alga .... 60 



a. Myxophyceae 



b. Chlorophyceae 



C. Constancy of Algal Constituents ... 63 



D. Displacement of Algae within the Thallus . '64 



a. Normal displacement 



b. Local displacement 



e. non-gonidial organisms associated with 



Lichen Hyphae 65 



F. Parasitism of Algae on Lichens . . , . 65 



CHAPTER III 



MORPHOLOGY 



I. GENERAL ACCOUNT OF LICHEN STRUCTURE 



ORIGIN OF LICHEN STRUCTURES 



A. Forms of Cell-Structure ... -67 



B. Types of Thallus 68 



a. Endogenous thallus 



b. Exogenous thallus 



II. STRATOSE THALLUS 

 I. CRUSTACEOUS LICHENS 



A. General Structure ... ... 70 



B. Saxicolous Lichens jo 



a. Epihthic lichens , 



aa. Hypotliallus or protothallus, . 

 bb. Formation of crustaceous tissues 

 cc. Formation of areolae 



h. Endolithic lichens 



c. Chemical nature of the substratum 



C. CoRTicoLOus Lichens yj 



a. Epiphloeodal lichens 



b. Hypophloeodal lichens 



