HISTORY OF LICHENOLOGY. 



25 



the fructification of Lichens, and upon their characters, real 

 or supposed, they based rival theories of their reproduction. 

 This subject has been, until within the last few years, the 

 pons asinorum of Lichenologists, and without suitable means 

 of research, it could not fail to be a botanical problem of 

 insuperable difficulty. The absence of fact, however, did 

 not prevent the development of theory ; and for a consider- 

 able period there raged in the botanical world a discussion- 

 ary war as to the most probable physiology of reproduction 

 in Lichens. One faction of disputants, whose motto was 

 probably " omne vivum ex ovo," and who believed with Lin- 

 naeus, 



" Vegetabile omne flore et fructu instruitur, 

 at nulla species bis destituta," 



contended, on the ground of analogy, for the necessary 

 sexuality of organs ; and various authors endowed various 

 bodies, seated on the surface of the thallus, with the male 

 or complementary functions. The opposite faction, on the 

 ground of observation, denied the proof of the existence of 

 either male or female organs of any kind, and asserted that 

 Lichens were invariably propagated by means of isolated 

 cellules which were analagous, in regard to function, to the 

 buds, or prop ag vs (offshoots) of the higher plants. Between 



