64 GUIDE TO THE STUDY OF LICHENS. 



diligent study of the description of families. The 

 method of procedure in the identification of the 

 genus depends somewhat upon whether or not a com- 

 pound microscope is available. If a microscope is at 

 hand the genus may be determined from the examina- 

 tion of the spores, and incidentally, also, the algae. 

 All that is necessary is to take very minute bits of 

 the thallus and apothecium, tear them apart thoroughly, 

 mount in water and examine. If the fragments are 

 still too thick, carefully press upon the cover-glass, ac- 

 companying the pressure with a rotary motion of the 

 finger ; this will separate the tissue-elements sufficiently 

 to permit their being seen distinctly. If no microscope 

 is at hand, the only thing that remains to be done is 

 to do the best you can without it ; the " artificial 

 key " is especially prepared for those who are without 

 / a compound microscope. No attention need be paid, 

 in this latter case, to spore-characters and the alg£e ; 

 make use of the family-characters and generic charac- 

 ters given in Part II. 



After the genus is determined, it only remains to 

 identify the species. This is done by referring to 

 the descriptions of the species belonging to that genus. 

 The beginner must not feel discouraged should he be 

 unable to name all the species collected, it is not ex- 

 pected of him. The unnamed specimens should be 

 kept for future study, or they may be submitted to an 

 expert for identification. It is well to bear in mind 

 that the expert cannot afford to do this work gratis ; 

 in perhaps most instances he will be satisfied with a 

 duplicate set 



