Oct. 19, 1871] 
NATURE 
483 

Besides the fruits of laborious compilation, the work 
obviously contains a large amount of original research. 
There are no less than seventy-five species, varieties, or 
orms, described for the first time (though not necessarily 
in this volume) by Mr. Leighton himself ; many of these 
referring, however (as in the case of the Graphidec), ta 
varieties or forms that do not apparently require sepa- 
rate description and nomenclature. He has also 
given great attention to the action of certain che- 
mical substances on the thallus and apothecia, and 
has to a considerable extent employed the said re- 
action in his minor classification. Only those who 
have attempted similar works can understand the immense 
labour involved in their preparation ; and British botan- 
ists ought to feel, and doubtless do feel, themselves under 
great obligations to Mr. Leighton for undertaking and 
successfully executing so difficult a task. The present 
work has been published at Shrewsbury for and by the 
author himself—a procedure which enables a writer to 
escape the irksome and mischievous fetters sometimes 
imposed by publishers. But this circumstance—of local 
publication—is apt to be attended with certain counter- 
vailing disadvantages ; so that in the present instance it 
does not surprise us that the typography, paper, and 
binding—the general up-get of the volume—do scant jus- 
tice to all the author’s labours in its compilation. 
It is always an ungracious task to expose faults in a 
work that is, on the whole, excellent ; that has been a 
labour of love ; that embodies the fruit of much research ; 
and that could have been fitly undertaken by very few indi- 
viduals. But Mr. Leighton himself apparently invites 
co-operation, if not criticism, in order to the prepara- 
tion of a fuller and more accurate second edition ; and 
his present work contains defects of a character that 
seriously mar its usefulness to the student, and that no 
honest reviewer, if he is to be critical at all, would be 
warranted in passing without notice. It is then a very 
serious defect of the book that it contains no Index of 
Species and Varieties, alphabetically arranged after the 
manner of that in Mr. Crombie’s Enumeration. For small 
genera, containing not more than half a dozen species, it 
may be comparatively easy to find varza or communis, 
or any other type; but in large genera such as Lecanora. 
Verrucaria,and Lecidea, each containing from 73 to 233 
species, the student must carefully read that number of 
names, spread over 53 to 110 closely printed pages in each 
case, before he finds perhaps the species of which he is 
in search. Only the most ardent lichenologist, who has 
abundant leisure as well as patience at command, will 
care to take this amount and kind of trouble. The 
omission referred to is of such importance that we counsel 
Mr. Leighton to lose no time in issuing a full and legible 
Index of species and varieties as a supplement to the pre. 
sent work; and to avail himself of the opportunity, which 
we trust its rapid sale and extensive circulation will give 
him, of inserting such an Index in its proper place in a 
second edition. The form of the said Index should be 
that adopted by Crombie in his Catalogue of the British 
Lichens (1870), and not that of Mudd, in his Manual 
(1861), which is infinitely Jess easy to use. 
In his present work, Mr. Leighton assumes too high a 
previous standard of technical knowledge on the part of 
the student. How many beginners in lichenology are 
likely to know—without being informed—what our author 
means by a “glypholecine” epithecium, or “ bacilliform ” 
spores? In fact, there ought to be a Glossary, to explain 
the meaning of the technical terms employed throughout 
the work; and this is the more necessary, seeing that, 
unlike Mudd in his “ Manual,” Mr. Leighton gives no Intro- 
duction explanatory of the general structureand morphology 
of lichens. Further, the student cannot be expected to 
know by intuition the meaning of the abbreviations used 
by the author, such as B. ; Bohl. ; Zw. ; M.and N.; Arn. ; 
Fellm; Th.M. Fr.; Flk. D.L.,; Nyl. Syn., Scand. or 
Pyr. ; Hepp sporen ; and so forth. There ought certainly 
to have been prefixed a full explanation of all these, and 
similar, contractions ; which explanation would necessarily 
include a comparatively complete and most useful Lichen 
Bibliography. Again, there is no standard of form, size, or 
colour, We are told that certain spores are large, mode- 
rate, small, minute, or very minute ; and certain spermatia 
long, shortish, or shortly cylindrical. But in no case are 
measurements given; and the student has to form his 
own opinion as to the signification of these unscientific, 
vague, relative terms. He is left, moreover, to conjecture 
as to. what constitute the “ positive” and “negative” re- 
actions of hydrate of potash and hypochlorite of lime ; 
and as to what is a “ vinous” reaction of the hymenial gela- 
tine with iodine ! 
The work professes to give a “fud/ diagnosis” of each 
species. But that surely cannot be considered a ful? 
diagnosis, which systematically omits almost all reference 
to the important Secondary Reproductive Organs? In not 
a single species, so far as we have been able to discover, is 
there a full description of the Spermogones / Pycnides are 
not once mentioned in the volume ! No doubt in one or two 
species the character of the sfevmatia is sketched by a 
single term, or by other inadequate means, Thus in Ofe- 
grapha amphotera the spermatia are said to be “ different 
from O. vulgata;” but we are not told what is their 
character in O. vu/gata. There are certain large and im- 
portant genera in which the spermogones are not at all 
mentioned even in the diagnosis of the genus (e,g., Verru- 
caria, Cladonia, Collema, Leptogium, Opegrapha, and 
Graphis) ; while in others such a description as ‘ Sper- 
matia various” (e.g. in the Ramadlinez) conveys little or no 
real information! In a very few exceptional instances, 
among the higher Lichens, are spermogones or their con- 
tents described. Where the attempt is made, the result is 
singularly bald and unsatisfactory, and is obviously not the 
fruit of original investigation. And, further, the beginner 
will scarcely understand what is meant by crenated, oblong 
cylindrical, straight, curved, or slender spermatia, without 
plates, which are wholly wanting in the present volume, 
A student cannot be said to have acquired a “knowledge” 
of Lichens, who is ignorant of the characters of their 
Spermogones and Pycnides. Tothe biologist or physiolo- 
gist, therefore—to him whose object is to study the whole 
Natural History of a given Lichen-species—such omissions 
in a systematic work on a national Lichen-flora is one of 
primary importance. The author tells us that he aims at 
descriptions, which will “/facé/itate the stucent (sic. the 
italics being ours) in the ready and accurate determination 
of his specimens ;” that is to say, the naming or ticketing of 
them, which is something very different from imparting a 
knowledge of all their natural characters! The truth is 
