RECENT OBSERVATIONS ON THE GONIDIA QUESTION. 117 



but he declines to assent to the idea that an alga, Nostoc, 

 through the parasitism upon it of a fungal myceliimi, forms 

 the aggregate which, merely from custom, as he holds, we 

 please to call a Lichen. The Avhole is, accordingly, in his 

 view, a " special kind of partial alternation of generations," 

 which calls to mind certain of the phases of the complicated 

 fructifications in Algse. Different other conditions in the 

 Lichens are doubtless still to be exjiected. 



Nor does Miiller hesitate to regard the heteromerous 

 Lichens in the same way, and thus many of the beautiful 

 researches of Dr. Schwendener will, he holds, find a new and 

 more natural interpretation. In the high Alps, amongst 

 huge expanses of rocks, far removed from Avoods, where no 

 Ascomycetes occur, where algae are but rare, and mosses 

 scanty. Lichens are yet met with, often in great multitudes. 

 That view in such cases seems most reasonable which, in 

 conformity mth the foregoing conception, restores to the 

 Lichens their autonomy, and concedes to them the power of 

 reproducing themselves in two, perhaps in several, ways, 

 and makes their existence not merely dependent upon a 

 fortuitous parasitism. 



A very elaborate memoir bearing on the question, with 

 copious figures, has lately appeared from the pen of Dr. E. 

 Bornet. As an abstract of this most interesting communica- 

 tion has already appeared in "^ Grevillea,"^ it is unnecessary 

 to attempt to repeat at any length, or even to try to success- 

 fully condense, the substance of so extensive a memoir. 



The object of the author is to put forward a series of 

 observations, which he regards as fully confirmatory of the 

 parasitic theory in lichens, and as being, indeed, the only one 

 which satisfactorily accounts for all the established facts. 

 Passing in review a long series of lichens, first those with 

 chlorophyllaceous, then those with phycochromaceous goni- 

 dia, he avers that there is nowhere any evidence that these 

 ever originate from the hyphae, but, on the other hand, that 

 the union of the latter with the algee is a subsequent occur- 

 rence. He brings forward certain cases in which this union 

 is something more than any mere contact, and in which a 

 penetration by the hypha into the interior of the cell of 

 the alga takes place ; whereupon, an increase in its size 

 with a thickening of the wall ensues, succeeded by a 



1 Bornet, ' Uecherclies sur les Gonidies des Lichens,' in ' Ann. des Sciences 

 Naturelles,' 5 ser., t. xvii, p. 



2 'Grevillea,' No. 15, Sept. 1873, p. 36. 



