316 
THE JOURNAL OF BOTANY 
considerably—are they not said to climb trees in Australia in their 
efforts to influence plant-life ?—and after Darwin’s classical instance 
of cats and the fertilisation of clover, it is not surprising that rabbits 
where present should add to the complexity of the problems encoun¬ 
tered. The author points out the practical difficulties of defining 
biotic factors; but where flowering plants are under consideration, 
the parts played by bacteria and moulds in bringing about decay and 
in other ways affecting the soil might well have received more than 
passing mention. Even when Krakatau was first visited, it was not 
considered necessary to take notice of any saprophytic organisms 
which might be present; and in the present work only the obvious 
“terrestrial algae, lichens and mosses” are mentioned as the first 
colonists of dry areas. Also in such intensive study as is the main 
thesis of the book, the presence of mycorrhiza should at least have 
been hinted at. 
The last portion of the book is an attempt to indicate the type of 
work which might profitably be accomplished in schools. It reads 
attractively, ancl should prove valuable to those for whom it has been 
written. The remarks on “The wrong way to teach” (p. 176) are 
to the point with regard to the absurd idea, still too prevalent, that a 
character must be “ useful ” or must be an “ adaptation ”—anthropo¬ 
centric botany has had its day. The appendixes, which are more 
advanced in matter, a good list of references, and a full index, add to 
the usefulness of this well-printed convenient-sized book, which taken 
in conjunction with the Types of British Vegetation will lead to a 
more scientific knowledge of plants as living organisms in their 
natural homes. 
_ J. R. 
Dwarf and Slow-growing Conifers. By Murray Hornibrook. 
Pp. x-195, crown 8vo. (Country Life Library, 1923.) Price 
10s. Gd. net. 
The cultivation of pigmy conifers, a horticultural art we have 
chiefly learned from the Japanese gardener, is growing in popularity, 
no doubt largely owing to the present craze for rock-gardening in 
this country. Dwarf conifers are needed to complete every well- 
planned rock-garden, and it is therefore to the rock-gardener rather 
than to the botanist that this little book will appeal. There is, how¬ 
ever, much in it that will interest the student of plant-variation, for 
conifers, like many other plants, vary enormously in the seed-bed. 
The author makes it clear at the outset that there are two kinds 
of pigmy conifers ; viz., the artificially dwarfed trees one meets with in 
the florists’ shops, and the natural dwarf sports or seedlings, most of 
which have arisen in cultivation; the book before us is concerned 
only with the latter class. An introductory chapter sketches the 
history of dwarf conifers in this country, and is followed by notes on 
their propagation and culture ; then follow descriptions of 460 varie¬ 
ties and forms, with notes on their history and synonyms. Only 
about a dozen dwarf conifers were known to Loudon in 1838, and it 
is quite evident that a great number of the names now found in 
nurserymen’s catalogues represent only a comparatively small number 
