156 
REVIEW 
After a brief introduction, in which collecting methods, and the uses of 
chemical reagents in lichenology are described, a short history of the subject 
is given. The structure of the lichen thallus is then treated in a very compre- 
hensive manner; over one hundred and twenty pages are devoted to this and 
to vegetative reproduction. 
In about fifty more pages, an account is given of the methods of repro- 
duction by spores, and the results of many researches as to sexuality and the 
origin of the fruit body in lichens, are summarised. There is a chapter on cell 
products and general physiology, and subsequently the subject of the origin 
and evolution of lichens receives adequate treatment. 
The section dealing with classification will be particularly useful to the 
South African worker, as it enables the genera to be identified. No doubt 
many overseas botanists will wish that this part of the work could have been 
elaborated, and the entire lack of illustrations of the genera will be much 
regretted. 
An error occurs on p. 324, where Combea, one of the endemic Cape Roccel- 
laceae, is said to have “gonidia absent from the hypothecium.” This is the 
character of Pentagenella, Combea having a well defined gonidial layer below 
the hypothecium. The same error occurs in Zahlbruckner’s account of the 
Lichens in Engler and Prantl, Nat. Pfl. i, 1* (key to the genera of Roccellaceae), 
from which it has crept into several works. 
On p. 323, the apothecia of all Roccellaceae, except those of Roccellina, 
are said to be lateral. Combea is, of course, characterised by its large, terminal 
apothecia. 
The genus Dermatiscum (p. 330), is said to have two species, one in Europe, 
the other in America. The sulphur coloured, endemic Dermatiscum Thunbergii, 
Nyl., of Olif ant’s Bad and the Montagu Pass is not mentioned, though of 
considerable interest to South African students, owing to the quaint history 
of its “discovery” by Leighton in the Burchell herbarium at Kew, four years 
after the death of the famous collector. Leighton described and figured it as 
a new species, but it was subsequently identified by Nylander as being the 
“Lichen Thunbergii ’ ’ of Thunberg’s Flora Capensis, and had been described by 
Acharius no less than eighty years before. 
A very important feature of the present work is the section devoted to 
ecology, as it is in exactly this field that the South African worker can make 
much needed contributions to the science. The Cape Peninsula is almost unique 
in the variety of habitat which it affords in a very limited area, and a thorough 
study of the growth forms assumed by a single species under varied conditions 
of altitude, rainfall, and exposure to light would be of more than local interest. 
The ecological section is the most complete of its kind, containing a full 
account of almost all previous work on the subject. 
A bibliography, covering twenty-five closely printed pages, concludes the 
