PERIOD V. 1803-1846 n 



study of them by their singular mode of growth and organization, both of 

 thallus and reproductive organs, for which reason he finally judged that 

 lichens should be considered as a distinct Order of Cryptogamia. 



In his first tentative work 1 he had followed his great compatriot 

 Linnaeus, classifying all the species known to him under the one genus 

 Lichen, though he had progressed so far as to divide the unwieldy Genus 

 into Families and these again into Tribes, these latter having each a tribal 

 designation such as Verrucaria, Opegrapha, etc. He established in all twenty- 

 eight tribes which, at a later stage, he transformed into genera after the 

 example of Weber. 



Acharius, from the beginning of his work, had allowed great importance 

 to the structure of the apothecia as a diagnostic character though scarcely 

 recognizing them as true fruits. He gave expression to his more mature 

 views first in the Methodus Lichenum*, then subsequently in the larger 

 Lichenographia Universalia?. In the latter work there are forty-one genera 

 arranged under different divisions; the species are given short and succinct 

 descriptions, with habitat, locality and synonymy. No material alteration 

 was made in the Synopsis Lickenum*, a more condensed work which he pub- 

 lished a few years later. 



The Cryptogamia are divided by Acharius into six " Families," one of 

 which, "Lichenes," is distinguished, he finds, by two methods of propagation : 

 by propagula (soredia) and by spores produced in apothecia. He divides 

 the family into classes characterized solely by fruit characters, and these 

 again into orders, genera and species, of which diagnoses are given. With 

 fuller knowledge many changes and rearrangements have been found 

 necessary in the application and extension of the system, but that in no way 

 detracts from the value of the work as a whole. 



In addition to founding a scientific classification, Acharius invented 

 a terminology for the structures peculiar to lichens. We owe to him the 

 names and descriptions of " thallus," " podetium," " apothecium," " peri- 

 thecium," "soredium," "cyphella" and "cephalodium," the last word how- 

 ever with a different meaning from the one now given to it. He proposed 

 several others, some of which are redundant or have fallen into disuse, but 

 many of his terms as we see have stood the test of time and have been 

 found of service in allied branches of botany. 



Lichens were studied with great zest by the men of that day. Hue 8 

 recalls a rather startling incident in this connection : Wahlberg, it is said, 

 had informed Dufour that he had sent a large collection of lichens from 

 Spain to Acharius who was so excited on receiving them, that he fell ill 

 and died in a few days (Aug. Hth, 1819). Dufour, however, had added the 

 comment that the illness and death might after all be merely a coincidence. 



1 Acharius 1798. 2 Acharius 1803. 3 Acharius 1 8 10. 4 Acharius 1814. 5 Hue 1908. 



