PREPARATIONS OF LICHENS. 
33 
rare, or illustrative of some subject which has been under con- 
versation or controversy in scientific circles. If we mistake not, 
here is material to satisfy the requirements of these three classes, 
and we are very much mistaken if the most decided dilettante does 
not discover that the sections of Lichens which heretofore were 
only to him an empty name, are such marvellous and interesting 
pages in the book of life, that some of the lines will become 
imprinted upon his brain for ever. 
THE LTCHEN-FLORA OF GREAT BRITAIN, IRELAND, 
AND THE CHANNEL ISLANDS * 
Whether the highly fanciful views of Schwendener, B ornet, and 
other investigators, which reduce all Lichens to parasitic Fungi, prey- 
ing on stray Algae, and represent them as performing feats of capture 
and voraciousness, best illustrated by members of the animal king- 
dom, be accepted or not, this book on British Lichens will be found 
indispensable to the student of these plants. Lichens remain 
Lichens, in spite of this incongruous theory, presenting as distinct an 
individuality as is seen in any other branch of the vegetable king- 
dom, and will continue to offer a deeply interesting field of investi- 
gation to the Cryptogamic botanist. The rapid strides in the advance 
of science in this country, made within the last half-century, is 
nowhere more conspicuous than in the department of which this work 
treats. In the fifth volume of “ English Flora,” published in 1833, 
the whole of the known British species of Lichens numbered 413, 
whereas in this work of Mr. Leighton they number 1,133, exclusive 
of the forms and varieties. When we consider what a compara- 
tively small propQrtion of the botanists of Britain have given atten- 
tion to these humble plants, this progress is very surprising. Nor is 
it to be supposed the field is exhausted. Treasures doubtless remain 
to reward the industry of future students. Some of the oldest 
living botanists, who imagined they had exhausted the British 
Lichen Flora, and turned their attention to other classes of plants, 
view, with a certain degree of impatience, the multiplication of new 
species, and would throw doubt on their value ; but this must be 
attributed to the vexation of being left behind, as will inevitably 
happen if we stand still, by the advancement of science. We have, 
in Mr. Leighton’s new work, a complete diagnosis of the 1,133 
species, also of the varieties and forms of these, which make a total 
of 1,718. A new feature in this edition is the microscopic measure- 
ment of the spores. Notwithstanding the great variation in the 
size of spores in the same species, carefully taken measurements 
afford valuable help in determining a plant, for this variation is 
* Eev. W. A. Leighton. Third edition. Shrewsbury, 1879. 
