ii6 Chapters in Modern Botany chap. 



The lichenologists were indignant at this proposed 

 revolutionary demoHtion of their science, and defended the 

 traditional position stoutly from 1869 to 1873 ; but in that 

 year the leading algologist, M. Bornet, fully confirmed and 

 extended the results of Schwendener, showing, for instance, 

 that a single " lichen " might really contain three or four 

 distinct and familiar species of algae, overrun and woven 

 into a false tissue by a single mould ; while the lichenologist's 

 contention, that the green alga-like cells developed from 

 the fungus-like filaments, was shown to be based on incorrect 

 observation, the former being really only sucked by close- 

 fitting or ingrowing protrusions of the latter. Another 

 important proof was given by Stahl, who succeeded in 

 making lichens artificially, i.e. by taking a known alga, and 

 sowing a known fungus upon it ; a lichen, a kfiown Hchen, 

 was the result. How obstinately the controversy raged 

 is oddly commemorated in the still current edition of the 

 EncyclopcBdia Britannica ; thus the article Botany retains 

 the older view, while Fungi states the modern. Lichens 

 (of course by an eminent and conservative lichenologist) 

 returns to the traditional standpoint, while this is finally 

 corrected at Parasitism. That, however, no shadow of 

 doubt any longer exists on the matter is well shown by the 

 recent researches of Bonnier, who has not only repeated the 

 synthetic experiments of Stahl with all bacteriological 

 precautions, but varied them by substituting the protonema 

 or filamentous alga-like stage of the life-history of a moss 

 for the ordinary alga constituent. 



Since then it is not only possible to separate the algae 

 constituent, and to see it live independently while the fungal 

 one as naturally starves, but also to combine the two elements 

 into a unified life, we believe that a lichen is not a single, 

 but a double organism, — an intimate union of an alga and 

 a fungus, living in mutual helpfulness or symbiosis. After 



