THE HISTORY OF LICHENOLOGY. 11 



of the spermatial characters in classification. This 

 author, however, did excellent work in the morphol- 

 ogy of lichens. He was also the first to point out the 

 double affinity of lichens ; on the one hand they 

 showed a close resemblance to fungi, on the other to 

 algae. He published a list of all the known lichens, 

 which included 1,348 species, 298 of which were de- 

 scribed as new. Nasgeli (1847) classified lichens as 

 algae under the group Lichenaceae and placed them be- 

 tween the Confervaceae and Exococcaceae. Itzigsohn's 

 (1854) opinions underwent great change as regards 

 the spermagonia. At first he was inclined to look 

 upon them as parasitic fungi, abnormal spore-organs, 

 apothecia or even parasitic lichens. Subsequently he 

 stated that they were the antheridia analogous to 

 those of mosses, of which the spermatia were the 

 spermatozoa. Somewhat later he was inclined to be- 

 lieve that the gonidia were the female organs and the 

 spermatia the male organs. Species of the algae 

 Pleurococcus^ Ulothrix, and others, were supposed to 

 be free unfertilized gonidia. Tulasne (1852) gave us 

 a very complete and scientific memoir on the histol- 

 ogy of lichens. Lindsay (1856) wrote a most excel- 

 lent popular treatise on British lichens. A little 

 later Schwendener (1858-1868) began his morpho- 

 logical studies of lichens which were even more com- 

 plete than those of Tulasne. In 1868 Schwendener 

 came to the conclusion that the so-called gonidia of 

 lichens were nothing more nor less than simple-celled 

 algae and that the spore-bearing portion of the lichen 

 was a fungus living parasitically upon the algae. 



