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 

 h. From other lichens 



c. From other vegetation 



III. ASSIMILATION AND RESPIRATION 



A. Influence of Temperature .... 238 



a. High temperature 

 h 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 



CHAPTER VI 



BIONOMICS 



A. Growth and Duration of Lichens . . . 252 



B. Season OF Fruit Formation . . . . 255 



C. Dispersal and Increase .... 



a. Dispersal of crustaceous lichens 



b. Dispersal of foliose lichens 

 (.. Dispersal of fruticose lichens 



D. Erratic Lichens .... 



256 



258 



