( viii ) 
passing into 1, a Colourless Series, especially prominent and characteris- 
tical in the higher tribes; and 2, a Coloured Series, having its chief 
development in the lower; series which, tabularized, so as to exhibit the 
sporal analogies, will be found significant as well of the relations of the 
genera, as of the systematic value of the spores. 
It is yet important to distinguish between spores typically colourless 
and what are rather to be taken for decolorate conditions of spores typi- 
cally coloured. There are sufficiently well-ascertained instances of such 
decolorate spores; and we need perhaps scarcely hesitate to argue from 
them to some other cases in which the evidence is possibly less clear, and 
thus to keep entire certain natural genera. And, on the other hand, it is 
conceivable that a genus may rather be referable to the Colourless Series, 
notwithstanding that many of its species exhibit spores which, in this 
respect at least of colour, look often the other way. The genus Sticta 
—in all respects remarkable —combining, says Schwendener, with a 
very pronounced affinity between the species, such varied transitions and 
gross contrasts of structure, that one might well question the systematic 
significance of the anatomical characters concerned, ' is also, to no small 
degree, equivocal in the spores. 
Difficulties of this sort are however to be expected in every stage, 
from the first step, of our endeavours to study the life in nature. What 
responds to our intelligence there is indeed of kin to that intelligence, is 
the ideal; but the ideal imprisoned in, and subjected to all the inordinate 
fortuitousness of, the natural. We cannot reach any seemingly definite 
result, be it the determination of what we take for a species, or the refer- 
ence of such species to the higher groups to which it is assumed to 
belong, without becoming aware, first or last, to how great an extent 
whatever we have succeeded in doing is only tentative. It is enough 
then if the difficulties of a result, or a method, appear to be overbalanced 
by its advantages. To this the writer has only to add here, once more, 
the expression of his earnest conviction, that with all the new light 
which the researches of the last thirty years have thrown upon Lichen- 
ology, this study has not yet advanced so far as safely to neglect the wide 
views, divinations as we now know they often were, of the elder lichenog- 
» CEs gibt wokl wenige Gattungen, welche wie Sticta bei ciner so ausgesprochenen 
natiirlichen Verwandtschaft der zahlreichen Arten, doch so mancherlei Uebergdnge 
und so grosse Gegensdtze zeigen, dass man an der systematischen Bedeutung der 
betreffenden anatomischen Charactere zweifeln mochte.” (Untersuch. 3, p. 167.) 
