86 THE NORTHERN MICROSCOPIST, 
from any surrounding difficulties which are insuperable to a plea- 
sant, profitable, and useful study of them. ‘There are difficulties 
in the study of Lichens, and perhaps, some which are peculiar ; 
but, as in all things else, an unenlightened imagination magnifies 
them. ‘The chief obstacles here are two. These are the termino- 
logy and the determination, or the distinction of the species and 
varieties. The first is the common tax of knowledge in all her 
departments. You must master the phraseology before you can 
know the subject. The second is a difficulty which now, when 
it is the greatest on account of the many forms discovered the 
differences of which are small ; yet, it is the more easily overcome, 
because, the very growth of our Lichen-flora has resulted in a 
more natural and comprehensive classification, as well as in a 
better and more certain method of study. As, in other depart- 
ments of Nature, the microscope has here come to our aid; and 
now, by comparing the internal structure; the shape, size, and 
colour of the spores, with the outward features of the plant, the 
determination of species is more easily and correctly attained, 
than when such determination was made simply by observing the 
external characteristics alone. Beyond these two checks, the path 
in lichenology is comparatively smooth, and abundantly healthful 
and enjoyable. 
Lichens, are a class of plants in the secondary division of the 
vegetable kingdom. They belong to the Cryptogamia or flowerless 
plants. Their position in that division is between the fungi on 
the one hand, and the algz on the other. The difference between 
the Lichens and those two adjoining classes, is not so great that 
their boundaries are unquestioned. Nor yet, are their affinities so 
close that the Lichens are not clearly distinguished between the 
two. Nature has no sharp and fast lines in her divisions. Her 
boundaries generally overlap, and it is so here. The Lichens run 
into the fungi in the corticulose Verrucarez, and into the alge in 
the gelatinous Collemacei. In a new text book on Botany,* 
recently translated into our language, Lichens are no longer 
regarded as having a distinctive existence. Their position as a 
separate class of plants is spoken of as a thing of the past. They 
are here placed in the order of Ascomycetes, amongst the Fungi. 
This new departure in relation to Lichens, which, to say the least 
of it, is somewhat presumptuous as well as premature ; is founded 
upon a theory propounded by Schwendener some few years ago, 
and now well known amongst lichenologists as the ‘““Schwendenerian 
Theory.” Briefly expressed, this theory is that—Lichens are not 
autonomous plants ; not individuals, in the ordinary sense of the 
word, but a compound of filamentous hyphz of the fungi and the 
green matter of the alge. The medulla of the Lichen, is the sup- 
*Text Book of Botany. Prank & Vines, 1880, 
