CHAPTER II CONSTITUENTS OF THE LICHEN THALLUS
A. HISTORICAL ACCOUNT OF LICHEN GONIDIA 21
C. CULTURE EXPERIMENTS WITH THE LICHEN THALLUS 24
D. THEORIES AS TO THE ORIGIN OF GONIDIA 25
I. NATURE OF ASSOCIATION BETWEEN ALGA AND FUNGUS 31 _a._ Consortium and symbiosis _b._ Different forms of association
J. RECENT VIEWS ON SYMBIOSIS AND PARASITISM 36
A. NUTRITION OF LICHEN ALGAE 39 _a._ Character of algal cells _b._ Supply of nitrogen _c._ Effect on the alga _d._ Supply of carbon _e._ Nutrition within the symbiotic plant _f._ Affinities of lichen gonidia
D. CONTINUITY OF PROTOPLASM IN HYPHAL CELLS 51
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
D. DISPLACEMENT OF ALGAE WITHIN THE THALLUS 64 _a._ Normal displacement _b._ Local displacement
E. NON-GONIDIAL ORGANISMS ASSOCIATED WITH LICHEN HYPHAE 65
B. TYPES OF THALLUS 68 _a._ Endogenous thallus _b._ Exogenous thallus
B. SAXICOLOUS LICHENS 70 _a._ Epilithic lichens _aa._ Hypothallus or protothallus _bb._ Formation of crustaceous tissues _cc._ Formation of areolae _b._ Endolithic lichens _c._ Chemical nature of the substratum
C. CORTICOLOUS LICHENS 77 _a._ Epiphloeodal lichens _b._ Hypophloeodal lichens
B. CORTICAL TISSUES 82 _a._ Types of cortical structure _b._ Origin of variation in cortical structure _c._ Loss and renewal of cortex _d._ Cortical hairs
D. MEDULLA AND LOWER CORTEX 88 _a._ Medulla _b._ Lower cortex _c._ Hypothallic structures
E. STRUCTURES FOR PROTECTION AND ATTACHMENT 91 _a._ Cilia _b._ Rhizinae _c._ Haptera
F. STRENGTHENING TISSUES OF STRATOSE LICHENS 95 _a._ Produced by development of cortex _b._ Produced by development of veins or nerves
Cortical Structures _a._ The fastigiate cortex _b._ The fibrous cortex
B. SPECIAL STRENGTHENING STRUCTURES 103 _a._ Sclerotic strands _b._ Chondroid axis
B. TISSUES OF PRIMARY THALLUS 112 _a._ Cortical tissue _b._ Gonidial tissue _c._ Medullary tissue _d._ Soredia
B. STRUCTURE OF THE PODETIUM 114 _a._ General structure _b._ Gonidial tissue _c._ Cortical tissue _d._ Soredia
C. DEVELOPMENT OF THE SCYPHUS 117 _a._ From abortive apothecia _b._ From polytomous branching _c._ From arrested growth _d._ Gonidia of the scyphus _e._ Species without scyphi