ADJUSTMENT OF ORGANISMS TO ENVIRONMENT 395 



Scrape a little of the whitish powdery substance covering 

 the surface of the chimney lichen, and mount it on a slide in 

 water; spread it out thin by pressure (with rotation) upon 

 the cover glass, and study the dissociated fragments. These 

 should be little groups of algal cells intertwined with fungus 

 filaments — lichen buds (soredia): in short, minute lichens, 

 ready for dispersal. Obviously, when the spores of the 

 fungus upon germination have to find and attach themselves 

 to the proper algal cells there are some exigencies to be met 

 that are obviated by this method of starting new plants 

 by means of soredia. 



The record of this study may well consist in some diagrams 

 and drawings of the facts demonstrated. 



Fig. 230. Nest of song sparrow containing three sparrow eggs and one 

 cow bird egg. Photo kindly loaned by Professor C. H. Eigenmann. 



