Revieww 301 
preface. The exhaustive bibliography of books and papers, all 
of which are cited in the text, also bears witness to the compre- 
hensiveness of the volume. : 
It is in the preface that Miss Smith expresses an opinion that 
her method has somewhat overburdened the pages with cita- 
tions, but it is more than probable that the student will regard 
this important feature of her book as a veritable mine of wealth. 
In the pages of the introduction (pp. xxiii to xxviii) the author 
expresses a definite view, which one would expect, regarding 
the relation of fungus and alga as it exists in the lichen thallus. 
It is that “‘Each symbiont contributes in varying degree to the 
common support,” but, there is clear evidence throughout the 
book that no attempt is made unduly to press the writer’s 
personal opinion. 
One of the most ably written chapters is that on phylogeny, 
a subject that is admittedly difficult to write about in clear and 
simple language, but Miss Smith does so without overburdening 
the chapter with unnecessary technicalities and in such a manner 
that the argument can be followed by the botanist who has no 
special knowledge of systematic lichenology. 
The chapter devoted to Ecology gives a resumé of the present 
knowledge of the ecology of lichens arranged under appropriate 
headings. Numerous citations are given. Whether the papers 
referred to have been of the kind that add to the data already 
accumulated, or of those that theorise on what is already known, 
all have received recognition. 
The illustrations, 315 in number (some of which are line block 
and others process reproduction of photographs) have not 
always the merit that one expects to find in a book of this class. 
The most favourable position for an illustration is by the printed 
matter that it is intended to illustrate, but this juxtaposition 
should not be made when the paper of the book proves un- 
suitable, as it certainly does, in this case, for process work. 
The appearance of the book would have been greatly enhanced 
had the photographs, on suitable paper, been inserted at the 
end of each chapter. 
It is cause for regret that the book, which at once proves itself 
to be indispensable to all lichenologists, could not be produced 
at a much lower price than that at which it is published. 
This volume together with the Monograph of British Lichens 
(two volumes) gives a fuller perspective of the important and 
laborious work that was undertaken by Miss Smith. One be- 
comes more fully aware of the firm grip and the discriminating 
critical knowledge that have been exercised in the writing of 
this trilogy, and the writer is to be heartily congratulated on 
the completion of this part of her work. 
Rate 
M.S. 20 
