however, again subdivided into seven divisions, to which two more 

 were added at a later period. Linne's system is of special impor- 

 tance, because it shows the first attempt at a natural arrangement. 

 Beginning with Graphis, which he probably supposed to be the 

 lowest form, he gives an ascending series terminating with Usnea, 

 which is certainly a highly developed lichen. Nearly all authors 

 of this period, subsequent to 1753, adopted Linne's system of 

 classification. 



The most remarkable characteristic of this period was the re- 

 newed uncertainty as to the position of lichens in the vegetable king- 

 dom. Some authors classed them as fungi, others as algae, again 

 as mosses. This doubt as to their true position continued to agi- 

 tate the minds of botanists, and it has not been definitely removed at 

 the present writing. 



It would be impossible to review all the works on botany issued 

 •during this period which incidentally treat of lichens. As yet no 

 specialists in the study of lichens had arisen ; in fact, all the crypto- 

 gams were very much neglected. The study of higher plants of 

 economic and of real or imaginary medicinal value absorbed the at- 

 tention of botanists. The great systematists, in particular, took no 

 interest in the lower forms of plant life. Linne designated lichens 

 as " rustici pauperrimi," which may well be rendered "poor trash" 

 of vegetation. In his " Species Plantarum " only eighty-six species 

 are mentioned, although 170 were known at the time. 



Progress in the study of the anatomy and physiology of lichens 

 was especially slow and unsatisfactory although these divisions of 

 botany were already known. Many botanists seemed possessed with 

 the idea that there must be an analogy between flowering plants and 

 lichens ; hence efforts were made to find the male and female repro- 

 ductive organs, fruit and seed. Wild and fantastic conjectures were 

 made as to what structures in lichens should be compared to special 

 organs in higher plants. Naturally, opinions differed very greatly. 

 Micheli looked upon the soredia as " pollen dust," the apothecia were 

 supposed to be the floral receptacles ( receptacula jlorum) , the spores 

 the true " flowers." As already mentioned, this 'author also explained 

 the asexual propagation of lichens by means of the soredia. Dillen, 

 whose work was likewise of considerable importance, believed that 

 the soredia constituted the pollen. His opinions in regard to the 

 apothecia varied. At one time he supposed them to be the recepta- 



