232 
THE DICTIONARY OF GARDENING, 
> 
Protoplasm—continued. 
The chemical composition of Protoplasm is very com- 
plex. It belongs to the group of substances similar in 
nature to white of egg, or albumen. It is very similar 
in its properties in plants and in animals, in which latter 
it has been called “sarcode” (from sar, flesh). When 
laid in a solution of iodine, it becomes yellowish or pale 
yellowish-brown. Dyes, such as magenta, eosin, and other 
aniline colours, carmine, logwood, &c., very generally 
colour dead Protoplasm readily, especially the nucleus ; 
but the living substance resists their action. A dilute 
solution of caustic potash dissolves Protoplasm, and is 
therefore often used, in microscopical work, to clear it 
out of sections where the chief desire of the operator is 
to see the arrangement of the cell walls only. Other 
tests for distinguishing Protoplasm are also occasion- 
ally used; but for these, inquirers are referred to such 
works as Sachs’ “Textbook of Botany,” Henfrey’s 
“ Elementary Course of Botany,” Bower and Vine’s 
“ Practical Botany,” or other works dealing technically 
with the subject. 
PROUSTIA (named after Proust, a Spanish chemist, 
who died in 1826). ORD. Composite. A genus consist- 
ing of six or seven species of stove or greenhouse, erect 
or climbing, hoary-tomentose or glabrous, sometimes spiny 
shrubs, natives of South America and Mexico. Flower- 
heads small, sessile, homogamous, disposed in much- 
branched or thyrsoid panicles at the ends or sides of 
the branches; receptacle naked; corolla bilabiate, with 
the segments revolute, the outer three- or four-toothed, 
the inner lip deeply two-parted; achenes turbinate or 
oblong, five-ribbed, with a pappus of copious sete, The 
under-mentioned species—the only one yet in cultivation 
—is a desirable greenhouse climber. For culture, see 
Mutisia. 
. pyrifolia (Pyrus-leaved).* f.-heads white ; s purple. 
l. petiolate, round-cordate or oval, tomentose beneat! Ap raa 
iaceous, densely tomentose irregularly 
eath, entire or 
ed. Chili, 1865. (B. M. 5489.) 
PROVENZALIA. A synonym of Calle. 
PRUINATE, PRUINOSE. Covered with glitter- 
ing particles, as if frosted over. 
PRUMNOPITYS. Included under 
(which see). : 
PRUNELLA (altered from Brunella, derived from 
the German Die Braiine, a disorder in the jaws and throat 
. which the plants were supposed to cure). The correct 
‘spelling, according to Bentham and Hooker, is Brunella, 
Self-heal. ORD. Labiate. A small genus (two or three 
species) of broadly-dispersed, decumbent or sub-erect. 
perennial herbs. Flowers purplish, bluish, or white t 
calyx tubular-campanulate, two-lipped ; corolla tube ample 
often exserted, the upper lip erect, concave, the lower 
spreading ; whorls six-flowered, in dense, terminal spikes 
surrounded by broad, imbricated bracts. Leaves entire 
incised-toothed, or pinnatifid. The species are well 
adapted for ornamenting rockwork, or the front of a 
flower border. They thrive in any light, rich soil, and 
may be readily increased by divisions, ` 
P, e-flow LA i 
—— 
August. Z petiolate, ovate, often toothed, ially at the base, 
This scarcely differs ftom Z ular, of which it eee eo 
variety. (B. M. 337; F. D. 1933) Bier Oy A 
* 
purple, 
than those of 
Hangclinear "oF lanceolate, “entire, rigor pia —* 
—— — y long, | Mediter- 
nays 
Podocarpus — be practised, depends very much on the subject 
PRUNING. Pruning consists in removing any part 
of a tree, either stem, branches, or roots, with a view 
to repressing growth in one direction, and directing the 
course of sap towards other parts of the tree which are 
better situated and constituted for performing the natural 
functions. The work is one of the most important in 
gardening, but, when the several habits and modes of 
fruit-bearing adopted by cultivated trees are understood, 
it is by no means difficult. Pruning is essential where 
trees have to be subjected to artificial treatment in a 
limited space, as in gardens generally, where, for 
example, a Plum-tree may be grown against a wall, or 
as a bush, pyramid, or standard. These shapes are 
produced by a combined system of Pruning and train- 
ing to prepare trees for filling the several positions 
assigned them, and contributing a crop from one and 
all. There are several objects in Pruning, ‘and the 
results attained vary exceedingly from the time and 
manner in which the work has been performed, and from 
other causes, some of which are beyond control. The 
thinning and removal of superfluous and useless shoots, 
with a view to admitting light and air, which are essen- 
tial for insuring productiveness; the affording of en- 
couragement towards promoting the formation of blossom- 
buds on branches hitherto barren; the modification of 
form in trained trees; the enlargement of fruit; the 
removal of dead, dying, or diseased branches, and many 
other such operations, may be cited as objects for which 
ing may be performed. One of the immediate 
effects of Pruning is to divert the course of the sap, which 
has hitherto been utilised by the branch removed, into 
others which are left; this causes them to strengthen 
and enlarge, which is one of the results generally aimed 
at. Inthe management of fruit-trees, the art of Pruning 
has a most important bearing, as, under artificial treat- 
ment, these have often to be cultivated in a limited 
Space, and trained to a shape not in accordance with 
their natural habits. Again, on the system of man- 
agement, in respect of thinning and removing the use- 
less wood, and exposing that left to become well ripened, 
depends materially the state of the crops annually 
Secured. The extent to which Pruning may with ad- 
under treatment, its rate of growth, and many other 
local circumstances. Some practitioners recommend & 
free, others a moderate, use of the knife; and others, 
again, use it as little as possible consistent with keep- 
ing their trees within bounds and preserving an evenly- 
d head. On a subject capable of such a wide 
and varied application, this is scarcely to be wondered 
at; and as different soils and localities have their own 
influence over the trees grown in them, so 
does the proper system of treatment vary somewhat in 
detail. Although hard Pruning is not here recommended, 
_ it is considered essential that the system must be mode- 
rately practised, and the work conducted with a view to 
Preserving an equality and symmetry amongst the branches, 
which shall also, at the same time, promote gpr and 
fertility, Young trees are invariably disposed to produce 
more branches than space can be provided for. By thin- 
ning out those which are weak and misplaced, addi- 
tional nourishment is supplied to the others, which may 
—— to develop, and remain almost, or quite, * 
length, Where the system of training to be adopt 
cannot be commenced because of the shoots being a = 
: — disposed, Pruning must be resorted to, ane 
it . Sap thereby caused to flow more freely where 
18 required. If a young fruit-tree can be grown. 
On without much cutting, until it arrives at a bearing — 
State, it has, usually, much cleaner and healthier 
branches, which, of course, are more favourable to frui h 
than others developed under a — may 
frequent amputation, however much 
sary in training to a desired shape. 
= 
