OcTOBER 2, 1913] 
NATURE . 
os) 
7 
tends to make food go bad more quickly when it 
is re-exposed to the ordinary temperature. Cold 
does not improve articles already commencing to 
decompose; but, on the other hand, if scientifi- 
cally carried out—that is, if the food is in excel- 
lent condition to begin with, and is preserved with 
all due precautions as regards the correct tem- | 
| to a subject which in former times was presented 
perature, its uniform maintenance, and the proper 
hygrometric condition and frequent re- 
newal of the air in the store-room, and 
if the lowering and raising of the tem- 
perature do not take place too sud- 
denly—no harmful consequences follow 
refrigeration. F. Soppy. 
THE NATURAL HISTORY OF A 
LONDON SUBURB.} 
HE increasing demand for works 
on local natural history, of which 
class of publication the present 
volume is an_ excellent specimen, 
must have been noted by workers in 
science as a healthy sign of popular 
awakening. But while in the eigh- 
teenth century it was possible for 
a Gilbert White to cover the whole 
ground so far as concerned his own 
district, the great development of 
specialised knowledge in modern times 
necessitates the cooperation of many 
workers to produce such a volume as 
that under consideration. Thus, in 
addition to the opening chapter oni 
topography, by Messrs. Maynard and 
Findon (the hon. sec. of the natural 
history section of the society), there 
are ten chapters by different authors 
dealing respectively with the geology, 
climate, plant-life (three chapters), 
bird-life, mammals, &c., insects, mol- 
luscs, and pond-life together with a 
very useful bibliographical appendix. 
A commendable feature of the 
present work is the general introduc- 
tory section heading many of the 
chapters. By this treatment the reader 
is enabled to pass from the general 
to the special—a method which may be 
condemned by some critics as an in- 
version of scientific method but, in a 
local natural history, has the distinct 
advantage of enabling the general 
reader and the would-be student to 
realise that the local and restricted data 
supplied by his own district fit in to the 
larger and more comprehensive generalisations 
which scientific observers have built up from de- 
tailed observations over wider fields. The chapter 
by Mr. A. G. Tansley dealing with the vegetation 
(chap. iv.) is a very good example of the treat- 
ment referred to, as he begins with the ecology, 
1 “* Hampstead Heath: Its Geology and Natural History.’’ Prepared 
under the Auspices of the Hampstead Scientific Society. Pp. 328+xi plates+ 
3 maps. (London; T. Fisher Unwin, n.d.) Price ros. 6d. nt. 
NO. 2292, VOL. 92] 
Badger Earths in Ken Wood. From 
shows the relationship of the vegetation to the 
geological features, and then groups vegetation 
generally under the various types of “associa- 
tions ” before dealing with the particular plant- 
associations of the district. The lists of species 
then come as natural sequences to the various 
“associations.” A living interest is thus imparted 
‘* Hampstead Heath : Its Geology and Natural History.” 
in the uninteresting form of a catalogue of names, 
amounting, in fact, to nothing more than the 
statement of the occurrence of a certain species 
in a particular district, without any relationship to 
its environment or to its associates. The chapter 
on the trees and shrubs (chapter v.), by Mr. Hugh 
Boyd Watt, will surprise many readers as a revela- 
tion of the extreme richness of the district, all 
