ON THE LICHEN-GONIDIA QUESTION. 275 
the gonidia (or gonimia) that we perceive the vegetative life to 
he chiefly promoted and active, as for example (putting forth 
young parts and) creating colorific matter ; while, on the con- 
trary, those portions of the thallus remote from the gonidia or 
advanced in age — as best appears in incrassate crustaceous lichens 
— having lost their life, become entirely tartareous, forming as it 
were but 4 thickened deposits.’ Now as the gonidia of all lichens 
are normally covered by the filamentose tissue, while in many a 
continuous cortical stratum entirely surrounds the other por- 
tions of the thallus, it is evident that, thus isolated from the 
outer world, they can derive nutriment for their growth and 
increase only from the thallus itself, to whose nutrition, accord- 
ing to Schwendener, as already intimated, they should them- 
selves subserve. But, as is very aptly observed by Th. Fries, 
1. c., p. 5, 44 It is very well known that other plants, from which 
parasites draw their nourishment, become in consequence 
languid, sicken and die, while here we see plants (algal colonies) 
on all sides infested by parasites (fungi), which not only do not 
suffer any injury, but are even so incited and stimulated that 
they grow, increase and multiply all the more.” Well may he 
exclaim, 44 a useful and invigorating parasitism — who ever before 
heard of such a thing ? ” Add to this, that, as shown by 
Nylander at considerable length in 44 Flora,” 1874, pp. 59-61, 
lichens derive their nourishment directly from the atmosphere 
(receiving nothing from the substratum unless as if mechani- 
cally, e.g. iron and lime), and that this penetrates chiefly through 
the surface (the cortical stratum) of the thallus to the gonidial 
stratum where the active life chiefly has its seat, and it is 
clearly demonstrated that Schwendener’s idea is not only a 
'priori most improbable, but also a posteriori entirely erroneous. 
But another strong objection has been made on the score of 
the distribution of lichens. On this point Krempelhuber argues 
that as many lichens are cosmopolitan, and as their gonidia are 
everywhere alike, it must, on the Schwendenerian hypothesis 
that these are algae, be assumed that such algae have as wide and 
general a distribution as the lichens, and that this being 
entirely contrary to our present knowledge of algal distribution, 
is in the highest degree improbable. Moreover, and as bear- 
ing more directly upon this argument, it may quite pertinently 
be asked, how is it that lichens, if the composite plants repre- 
sented, are met with in situations where neither algae nor fungi 
are seen ? This has been very distinctly put by Dr. Muller, 1. c., 
where he observes that in the high Alps, amongst huge ex- 
panses of rocks, far removed from woods, where no Ascomy- 
cetes occur, and where algae are but rare, lichens are often met 
with in great abundance. This is amply confirmed by our own 
observations amongst the higher Grampians in Braemar, where 
