128 JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. [ February 17,1881. 
of turfy loam, peat, and sand, such as is prepared for the ma¬ 
jority of allied Rutaceous plants from the southern hemisphere, 
thorough good drainage, and careful supplies of water are re¬ 
quisite ; and with attention to these matters, and ensuring the 
maturing of the growths in summer, either by placing the plants 
out of doors on a firm bottom of ashes in a slightly sheltered 
position where protection can be afforded from heavy rains, or 
by arranging them in a cool well-ventilated portion of the green¬ 
house, satisfactory results can be readily obtained. 
Correa cardinalis was so named by Dr. Ferdinand Mueller, the 
well-known Australian traveller, who found it in several districts 
of that continent, particularly Victoria and Gipps’ Land. Seeds 
were sent to Messrs. Veitch at Exeter about 1854, from which 
plants were raised and distributed.—L. 
THE RESULTS OF HORTICULTURE. 
In our rambles on the south coast we may occasionally meet 
with Brassica oleracea, a small unattractive plant, but of inesti¬ 
mable value on account of its being the parent of a large section of 
culinary vegetables which have contributed so much towards the 
health and sustenance of the population. All our fine Cabbages, 
Cauliflowers, Broccoli, Brussels Sprouts, Scotch Kale, and some 
Borecoles owe their origin to this little weed. Had not some acci¬ 
dental circumstances brought this plant under the observation of the 
horticulturist, it might have remained in its native haunts to this 
day, and we should not have known these indispensable additions 
to our gardens that we now possess. It is very strange what 
varied forms have resulted from cultivation, and what a small 
resemblance some bear to the original: some are quite hardy 
while others are destroyed by frost, and they have adapted 
themselves to our requirements in a surprising degree, so that we 
may have them in season the whole year round. What appears 
most strange is that these varieties have almost constituted dis¬ 
tinct species by retaining the power to reproduce their characters 
from seed. Most horticultural productions show a tendency to 
return to the original, but with the Brassicas the inclination is to 
stray further away and to sport into greater variation. When 
they are grown in large quantities for seed it is the custom to go 
over the rows and pull out what are termed rogues, which are 
those that show a slight variation from those intended for seed, 
but I fancy if those were planted by themselves some of them 
might prove useful additions. Every seedsman appears to have a 
collection of his own, and it is possible we may have something 
that will differ as much from a Cauliflower or Brussels Sprouts 
as they differ from the original parent. Although the external 
form has assumed such varied shapes the internal structure remains 
the same, as will be seen when in flower; and it may then be said 
that we do not know a Cabbage from a Cauliflower, and many 
would not from the flowers alone. In other tribes of plants credit 
is taken for having obtained crosses, but in the Cabbage tribe it 
is usually left to Nature ; yet something in that way might be 
done, although it is difficult with all things in the open air, but it 
deserves attention. 
Much may be said on the cultivation of each variety, but it is 
sufficient to show what great results have been obtained from a 
comparative insignificant origin. Also I should direct the attention 
of gardeners to the blanching of vegetables. Many are rendered 
more palatable and delicate by being blanched, and I think others 
may be added to our list if experiments are carried out in a 
judicious manner and proper attention is paid to the subject. 
THE EFFECTS OF ELECTRICITY ON VEGETATION. 
(Contilived from page SO .) 
The very great significance attaching to the terms “ positive ” and 
“negative ” render it all-important that the distinctive differences in 
their contending actions pertaining to the atmosphere should now 
be fully recognised and comprehended in order to sufficiently 
realise the results, for as everything in life and growth depends 
primarily on the contention of these two opposing forces, it is 
absolutely essential that they should be rightly understood. Their 
antagonistic powers may be likened to the planting a tree with 
one hand and pulling it up again with the other, or driving a nail 
with the face of a hammer and drawing it out again with the tail. 
For the plant, the positive condition prepares and provides the 
food, but it is the negative that causes its digestion and appropri¬ 
ation ; and should there be any check or cessation in either, so as 
to destroy the even balance, unhealthiness or even disease becomes 
the inevitable consequence. 
In order that there may yet be no further confusion of terms it 
will be desirable to restate the attendant results of these separate 
conditions of force. It has been observed that every electrified 
substance is invariably surrounded by an electric state of the op¬ 
posite character ; thus a positive is attended by a negative, and a 
negative by a positive. Then, again, in the electric decomposition 
of water, for instance, consisting of one volume of oxygen, which 
is a negative, to two volumes of hydrogen, and these being positive, 
the negative oxygen goes to the positive electrode, whilst the 
positive hydrogen passes to the negative. These consequently 
were designated by Faraday as “ions,” from the verb eo, I go— 
ions, going; hence, one class of elements become ions to the 
positive, whilst the other class are ions to the negative ; and in 
the decomposition of all compound substances whatever, they 
being composed necessarily of a positive and a negative, this 
rule is strictly adhered to, each one going to its respective 
quarters. 
It is commonly supposed that plants possess some kind of 
power that enables them to select their food as if they were 
endowed with intelligence sufficient to direct them in “ what to 
select and what to avoid.” That there is some degree of selection 
made is perfectly true, but then it is wholly in accordance with 
this law of electrolysis to which they are helplessly subservient, 
and most assuredly not by any power of volition on their own 
part ; hence it becomes perfectly easy and certain to be able to 
predicate the direction in which any particular elements will pass. 
With respect to the atmosphere, this is composed of two simple 
gases—oxygen and nitrogen, together with two other gaseous 
compounds—carbonic acid and water, the whole being more or 
less contaminated with soot, fungus spores, and minute particles 
of dirt of almost every description. It is, however, only the two 
former gases which constitute the atmospheric air proper, the 
others being adjuncts, continually varying in their proportions. 
These, however, are but the “ materials ” of growth ; the “ modi- 
fying principles,” alluded to by Sir Humphry Davy, consist in 
the atmosphere being charged with electricity. 
Unlike water, the gases of which are combined together chemi¬ 
cally, the gases of atmospheric air are only mixed together 
mechanically, so that the least possible degree of attraction 
is enabled to separate and appropriate the oxygen, as also the 
nitrogen. The extreme wisdom of this arrangement is manifest 
in thus providing a starting point, requiring only the smallest 
possible amount of force to upset that stationary equilibrium 
which, once dirturbed, goes on accumulating in intensity, like the 
stone rolling down hill, until the highest working power has been 
attained. Then, in order to secure the breaking-up of the vis 
inertia; of these gases and to acquire the first step in the move¬ 
ment, the electricity of the atmosphere comes in- as an indispens¬ 
able agent. In its normal state the atmosphere is electro-positive, 
and consequently the earth beneath it is necessarily electro¬ 
negative. Now, the immediate consequence of these opposite 
states is that any substance placed partly in the earth and partly 
in the air becomes polar by induction, like the wire at page 355, 
and hence an attracting power is thus imparted to one end to the 
exclusion of the other, which causes it to seek out and combine 
with the oxygen chemically, leaving the nitrogen unaffected by 
its selection. In this chemical combination of elements a further 
degree of electrical force becomes developed, and this in its turn 
again leads, by induction, to a still greater measure, and so heaps 
up a continuous supply as the force becomes utilised in the pro¬ 
ducts of growth. The plant, situate with its roots in the ground 
and its head in the air, is first dependant on the air and the earth 
for its primary polarisation, and this again has to depend upon 
the intensity of the opposition, or amount of polar energy between 
the earth and the atmosphere. Hence, as dry vegetable matter 
is a very bad conductor, it is essential in the first place that the 
texture of the plant should be fairly supplied with moisture. 
Then as fluids charged with certain salts in solution are much 
better conductors than plain water, we have in this one means of 
exciting a more energetic degree of polarity. Following upon 
this the leaves and stems are made more powerfully attractive of 
oxygen as the next stage in the process. 
Now with respect to the atmosphere. This is continually vary¬ 
ing in its intensity as well as in its direction—that is, from posi¬ 
tive to negative and back again, and it is to these changes that 
we have to attribute the many fluctuations and differences of 
situation, as well as the various abnormal conditions of growth. 
When the gardener complains of “ want of strength in the air,” 
this want of electric energy is one great source of the weakness, 
if not the principal one. Leave a steel magnet without its soft 
iron keeper and it soon loses its magnetism ; but this may be 
speedily restored by rubbing it in a certain direction with another 
magnet. The same loss is ever being experienced by the atmo¬ 
sphere, but here it is renovated in a different manner. It was 
shown practically on the lecture table by Sir William Grove that 
