ON THE LICHEN-GONIDIA QUESTION. 273 
cultivation are thus inconclusive, what we believe to be the true 
connection between the filamentose tissue and the gonidia had 
been sufficiently established by the observations of Bayrhoffer, 
Speerschneider, Tulasne, Thwaites, Gribelli and others. Nay, 
De Bary himself, in his treatise 44 Morphologie und Physiologie 
der Pilze Flechten, und Myxomyceten,” p. 258, &c., had 
distinctly shown that the green gonidium originates in the 
expansion of a short lateral branch of the hypha, which becomes 
shut-off as a globular-cell, and acquires a green colour. This 
green matter Nylander in 44 Flora,” 1874, p. 7 6, asserts, as the result 
of observation, arises originally within the primary chlorophyll- 
or phycochrom-bearing cellule, and is not intruded from any 
external quarter. And that the gonidia themselves are not 
derived from any foreign source, will be sufficiently evident 
from a reference to Figs. 5 and 6 of our Plate, where in the 
case alike of a lichenaceous and a collemaceous species, it is 
apparent that they originate in the isidia ; for it is in the 
young isidia that they may be most conveniently studied and 
that their origin is most clearly seen. 
Once formed, as De Bary proceeds to show, the gonidium 
increases independently by division ; but though usually seen 
placed on the branchlets of the hyphse, yet this is not univer- 
sally the case, for a number of them eventually lie without 
stipites scattered between the hyphse. This has still more recently 
been confirmed by Th. Fries, 44 Lich. Scand.” p. 7, who, from 
direct observations, adopts and defends the opinion. For, as 
he states, the hyphse are not only elongated into filaments, but 
also send out short branches, of which the terminal cell 
gradually dilates, becomes subglobose, at length is filled with 
chlorophyll, is subsequently changed into a gonidium, which 
finally is variously divided and gives origin to other gonidia. 
With respect also to a number of these gonidia being found 
free and scattered amongst the hyphse, the same author rightly 
argues that this circumstance is by no means antagonistic to 
the opinion that there is normally present a connection between 
the gonidia and the hyphse. As bearing also upon the point in 
hand, Krempelhuber, 1. c., observes that Schwendener does not 
attempt to explain from what source the fungal hyphse, which 
involve the green algse, are derived. On the assumption, 
however, that he would explain it by asserting that the filaments 
produced from the germinating lichen-spore are the hyphse of 
the first rudimentary thallus, he urges that the idea of such 
hyphse going in search of an algal host, and giving rise to a 
lichen-thallus with fructification, is inconceivable. Moreover, 
there are species of lichens which in many countries never 
fructify, and whose propagation can consequently be carried on 
only by means of the soredia, and the hyphse of such could in 
VOL. XIII. — NO. LII. T 
