446 
opment of lichens. It is practically impossible to determine what 
free fungi are identical with the fungi of lichens. A\ll investigators 
in this line have met with very unsatisfactory results, a thing natur- 
ally to be expected. According to Tavel* the fungi of the Colle- 
maceae, Arthoniae and Lecideaceae are more or less closely re-. 
lated to the Patellariaceae. The relationship of the fungi of the 
Pertusariae, Lecanareae, Pannarieae, Umbilicarieae, Peltidiaceae, 
Parmeliaceae, Usneaceae, Cladoniaceae, Sphaerophoreae, Ephebeae 
and Lichineae is practically unknown. The Verrucarieae, De- 
campieae and Endocarpieae are related to the Amphisphaeriae, 
Sphaerelloideae. Such uncertainty is certainly very unsatisfactory 
Although there may be algae, such as Cystococcus humicola, 
Pleurococcus vulgaris, Nostoc lichenoides, etc., which only await the 
opportunity to unite with some fungus to form a lichen, yet it is 
evident that no true Ascomycete has the power to enter into such 
aunion. There is great uncertainty as to the exact method by 
which the first lichen or lichens were formed. The author makes 
the following hypothetical assumption: “In the beginning several 
lichens were formed by the union of true fungi with algae. Ac- 
cording to Moller} such a process is now going on in the case of 
Cora pavonia and the related forms of Dictyonema and Laudatea 
The gelatinous lichens are very likely the oldest forms of the 
Ascolichenes. Such a gelatinous lichen took its origin as the re- 
sult of the parasitic union of a fungus and a spherical colony of 
Nostoc lichenoides. The question of the origin of the fungus coin- 
cides with the question of the phylogenetic origin of parasitic 
fungi in general and need not be further discussed. The fungus 
which at first behaved: like a true parasite (antagonistic symbiosis) 
took its entire food-supply from the nostoc. The condition of 
mutualism (consartism) was a phylogenetic product ; perhaps due 
to natural selection or other formative causes resulting from 
the union of alga and fungus. From this proto-Col/ema other 
gelatinous lichens were evolved; finally also such with hetero- 
merous thallus. It is probable that in the course of phylogenetic 
rs *Tavel, F, Vergleichende Morphologie der Pilze, pp. 94 and 108. Jen% 
1892. : 
 } Mater, A. Ueber die eine Thelephoree, welche die Hymenolichenen: Cora 
Dictyonema und Laudatea bildet. Flora 77: 254-278, 1893. cae 
