xiv CONTENTS 



PAGE 



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 ... . . V. 245 



a. Colour given by the algal constituent , 



/'. Colour due to lichen-acids 



c. Colour due to amorphous substances 



d. Enumeration of amorphous pigments 



e. Colour due to infiltration 



CHAPTER VI 

 BIONOMICS 



A. GROWTH AND DURATION OF LICHENS . . . 252 



B. SEASON OF FRUIT FORMATION. . " . . 255 



C. DISPERSAL AND INCREASE .' . . - . . 256 



a. Dispersal of crustaceous lichens 



b. Dispersal of foliose lichens 



<,. Dispersal of fruticose lichens 



-D. ERRATIC LICHENS .... . 258 



