THE HISTORY OF LICHENOLOGY. 7 



first chemical studies of lichens. He found that they 

 contain such organic substances as oil, resin and 

 mucus and various inorganic salts. In the year 1810 

 Acharius issued his " Lichenographia Universalis," 

 which was the most voluminous and complete work 

 on lichens yet issued. It is simply a manual of lichens 

 with rather imperfect descriptions of species. His 

 illustrations, particularly those of the spores, are poor. 

 One would expect better work from so eminent a bot- 

 anist. He did not make use of the spore-characters 

 in his system. Other eminent botanists, as Lamarck, 

 De Candolle, Fries, F^e and Eschweiler, established 

 systems of classification ; all of which were artificial 

 and inadequate. 



Some of the leading botanists of the time believed 

 that lichens were related to fungi as well as to the 

 algae. Accordingly Agardh, Voigt, Endlicher, Lind- 

 ley, Reichenbach and others considered lichens as a 

 distinct class to be placed between the algae and fungi. 

 Sprengel and Oken also considered them as a distinct 

 class but placed them between liverworts and algae ; 

 De Candolle placed them between liverworts and 

 fungi. Many other botanists still considered lichens 

 as a subordinate group belonging to various natural 

 classes, as algaj, fungi, mosses, etc. 



At the beginning of the nineteenth century the 

 belief in spontaneous generation was quite general. 

 Sprengel and others were convinced that, under favor- 

 able circumstances, lichens were evolved from decaying 

 substances, or the decomposition of water. Agardh 

 (1820), the eminent algologist, stated that he had 



