230 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
of which “tends to encourage that spirit of observation—that 
desire to know—which is so essential to a useful career.” 
The work is divided into forty-six short chapters, averaging 
only six and a quarter pages each, so that the beginner can 
never be fatigued by having too much of any subject at one 
time; and the chapters are conveniently grouped into eight 
sections, respectively dealing with geology and _ soil-science ; 
growth, reproduction, planting, and treatment of arborescent 
plants; management, measurement, and realisation of timber- 
crops; the identification of trees; descriptive details regarding 
British forest trees, broad-leaved and coniferous (a section 
being devoted to each); insect pests; and parasitic fungi. 
There is a very thorough Index, occupying the perhaps 
disproportionate space of 30 pages, dealing with references 
to the matters contained in the 288 pages of letterpress. 
As is, of course, very appropriate in a book on trees, the 
portions dealing with botany are largely in excess of those 
treating of geology and zoology; and the sections descriptive 
of the different shapes of tree-leaves, and the peculiarities of 
the chief kinds of British trees, occupy fully one-half of the 
volume. About 40 pages are devoted to insect pests, and 
the more important of these are described—the weevil, beetle, 
saw-fly, and bud-tortrix of the pine, the oak-leaf-roller, the larch- 
aphis, the ash-bark scale, the beech-coccus, the gall-flies, and 
the spruce-gall aphis. But only eight pages are devoted to 
the injurious fungi, and only one of these is described—though 
it is certainly that which has hitherto done the greatest amount 
of damage in Britain, the larch-canker fungus. The definition 
of a fungus as “a plant which depends upon another, or upon 
vegetable debris, for its sustenance” is incorrect, because (to 
give a homely example, such as every one may have often 
noticed) green mould will flourish on old boots kept in a warm, 
damp place, although these are neither plants nor vegetable 
debris. It would be more nearly correct, though perhaps 
not absolutely so, if one said that fungi were dependent on 
organic matter for their ability to vegetate. 
This casual mention of organic matter leads one to regret 
that Mr Curtis has not also included chapters on organic and 
inorganic chemistry, because, both in its relation to plant 
physiology and to the decomposition of rocks and the prepara- 
tion of soil for plant-food, chemistry is certainly a branch of 
