CHAPTER V

PHYSIOLOGY

I. CELLS AND CELL PRODUCTS

A. CELL-MEMBRANES 209 _a._ Chitin _b._ Lichenin and allied carbohydrates _c._ Cellulose

B. CONTENTS AND PRODUCTS OF THE FUNGAL CELLS 213 _a._ Cell-substances _b._ Calcium Oxalate _c._ Importance of calcium oxalate

C. OIL-CELLS 215 _a._ Oil-cells of endolithic lichens _b._ Oil-cells of epilithic lichens _c._ Significance of oil-formation

D. LICHEN-ACIDS 221 _a._ Historical _b._ Occurrence and examination of acids _c._ Character of acids _d._ Causes of variation in quantity and quality _e._ Distribution of acids

E. CHEMICAL GROUPING OF ACIDS 225 I. ACIDS OF THE FAT SERIES II. ACIDS OF THE BENZOLE SERIES SUBSERIES I. ORCINE DERIVATIVES SUBSERIES II. ANTHRACENE DERIVATIVES

F. CHEMICAL REAGENTS AS TESTS FOR LICHENS 228

G. CHEMICAL REACTIONS IN NATURE 229

II. GENERAL NUTRITION

A. ABSORPTION OF WATER 229 _a._ Gelatinous lichens _b._ Crustaceous lichens _c._ Foliose lichens _d._ Fruticose lichens

B. STORAGE OF WATER 232

C. SUPPLY OF INORGANIC FOOD 232 _a._ In foliose and fruticose lichens _b._ In crustaceous lichens

D. SUPPLY OF ORGANIC FOOD 235 _a._ From the substratum _b._ From other lichens _c._ From other vegetation

III. ASSIMILATION AND RESPIRATION

A. INFLUENCE OF TEMPERATURE 238 _a._ High temperature _b._ Low temperature

B. INFLUENCE OF MOISTURE 239 _a._ On vital functions _b._ On general development

IV. ILLUMINATION OF LICHENS

A. EFFECT OF LIGHT ON THE THALLUS 240 _a._ Sun lichens _b._ Colour-changes due to light _c._ Shade lichens _d._ Varying shade conditions

B. EFFECT OF LIGHT ON REPRODUCTIVE ORGANS 244 _a._ Position and orientation of fruits with regard to light _b._ Influence of light on colour of fruits

V. COLOUR OF LICHENS

A. ORIGIN OF LICHEN-COLOURING 245 _a._ Colour given by the algal constituent _b._ Colour due to lichen-acids _c._ Colour due to amorphous substances _d._ Enumeration of amorphous pigments _e._ Colour due to infiltration