568 JOURNAL OF HORTICULTURE AND COTTAGE GARDENER. c December n, usi 
Grape-growing, always an important branch of gardening, 
never before reached such a state of perfection ; but where now are 
the Pine Apples that used to have so much attention? Except in 
a few establishments they are not grown, and in the weekly 
calendars of the gardening papers, where they so long held the 
place of honour, they are seldom mentioned. Kitchen gardening 
has been always well done, but I question much if ever better 
vegetables were grown than now ; at least there were not so 
many varieties to assist gardeners in lengthening their seasoD.— 
J. MacDonald. 
AIGBURTH BRUSSELS SPROUTS. 
A yeae ago your esteemed correspondent Mr. Iggulden remarked 
that the above much-praised variety had, with him, in good soil, 
grown too strong, and produced sprouts so large, open, and coarse 
as to be unacceptable, and asked correspondents who had grown 
it on poor soil to state whether the produce was satisfactory. As 
far as I can remember no one replied, presumably because all who 
had had fared similarly to Mr. Iggulden. That was what was 
done here; but this year plants were put out early on very in¬ 
different soil, but still the results are unfavourable; so much so, 
in fact, that it never will again be grown here. The imported will 
be again resorted to, although a per-centage of such also comes 
useless. The fact seems to be, that Brussels Sprouts tend to revert 
to the type from which it sprang.—S. D. 
FLOWERS OF THE PAST SEASON. 
With me the past season has not been one of the most favour¬ 
able for plants in the flower garden ; and being reminded of the 
approach of another season, I wish to say a few words respecting 
some that have exceeded my expectations. 
Gaillardiapicta Lorenxeana. —Seeds of this were sown in heat, 
grown on as required, and planted out at the usual time, proved 
an acquisition both for beds and borders. It produced its variously 
coloured flowers through the summer until the frost stopped them. 
It is of dwarf habit, and was much admired by all who saw it. 
Linaria reticulata aurea purpurea. —Another very choice dwarf 
annual. Its beautiful flowers are very attractive, and with care in 
cultivation it proves a useful plant for beds and borders. If in¬ 
tended for bedding, the plants should be pricked out singly and 
moved with a ball to their destination ; but I prefer placing them 
singly in small pots. It seems to be at home everywhere in a 
garden. 
Papaver wmbrosa. —One of the richest crimson flowers we possess. 
It is treated as an annual, the seed being sown in the autumn and 
the young plants thinned to a few inches apart. It stands through 
our ordinary winters sown in spring, and we have a continuous 
display through summer and late autumn. 
Verbenas. —I find these are much better grown from seed than 
from cuttings. The seed should be sown in heat in early spring, 
and grown on. Planted out at the usual time I had a splendid 
bed of mixed colours of all shades. I intend in the future to rely 
on seed for my supply. By so doing I shall economise time and 
space. Through the winter of late years I have found it a difficult 
matter and almost impossible to succeed with plants and cuttings 
through the winter.—P. U. 
OF HUMUS. 
(Continued from page 547.) 
It is apparent from the facts cited in the letters which I have 
already addressed to you, that humus if not a direct food for 
plants (on which some obscurity still rests, high authorities ranging 
themselves on opposite sides on the question), there can be no doubt 
whatever that the functions performed by it in aiding the nourish¬ 
ing properties of other manurial constituents are most important. 
In the words of Liebig humus, as well as chloride of sodium, 
nitrate of soda, salts of ammonia, &c., “ besides the action peculiar 
to their elements, perform also a kind of digestive function com¬ 
parable to that of the stomach in animals, and in which they may 
partly replace each other. These substances, therefore, act bene¬ 
ficially upon those kinds of soil only in which there is a defect, 
not in quantity, but in the form and condition of the nutritive 
elements. They may, accordingly, in this permanent action be 
replaced by a mechanical comminution, or exceedingly fine pul¬ 
verisation of the soil. 
“ The term ‘ manure ’ is commonly used to designate all matters 
which, applied to a field, will increase the amount of its future 
produce, or when the land has been exhausted by cultivation will 
restore its capability of yielding remunerative harvests. Manuring 
agents act partly in a direct manner as elements of food, and 
partly, like common salt, nitrate of soda, or salts of ammonia, by 
enhancing the effects of the mechanical operation of tillage, so 
that they frequently exert as favourable an influence as the actual 
increase of the nutritive substances in the ground.”—( Liebig's 
“ Nat. Laws of Husbandry,” p. 131.) 
“For corn and summer plants, in order to obtain a maximum 
of produce, the presence of organised matter in the soil is of the 
utmost value. By the addition of sawdust the effect of the mineral 
manure was strikingly augmented, and it appears to me to be 
clear that the chief cause of this increased action must be looked 
for in the carbonic acid formed by the decay of the wood, which 
in this case acts not nearly so much as a source of carbon as by 
its solvent power for the earthy phosphates, and by converting 
into bicarbonates the neutral alkaline and earthy carbonates, and 
by rendering the silicates soluble. This carbonic acid is the con¬ 
dition furnished by Nature for the passage of these necessary parts 
of the food of plants into their organism, for the earthy phosphates 
and carbonates are only soluble in water when the water contains 
carbonic acid. The carbonic acid contained in rain water is 
obviously not sufficient to bring into the soluble form, which 
alone is fitted for assimilation by vegetables, the proportionately 
large amount of mineral substances absolutely necessary for a 
maximum development in summer plants, such as grain, during 
the short period of their growth. It is well known how great is 
the effect produced in this way even by moderate rains ; and we 
may easily calculate how greatly this action must be increased 
by the addition of carbonic acid, whereby the solvent power of 
rain water for these mineral substances is augmented a hundred, 
nay, a thousandfold. The carbonic acid of ordinary spring water, 
which often retains in solution such considerable quantities of 
inorganic matter, proceeds from the same source—namely, the 
decay of organic matter in the soil.” 
“ If to one acre English we add 8950 lbs. (about 4 tons) of the 
ashes (or of the ingredients of those ashes from other sources) of 
Wheat, Potatoes, &c., this large supply only suffices to give to the 
soil of the whole surface, to the depth of one foot, these materials 
in the proportion of 1 grain to each cubic foot. This is much 
less than is contained in a cubic foot of tolerably fertile soil; but, 
on the other hand, much more than is required for one crop. But 
since only that part of the manure acts which is in contact with 
the fibres of the roots, it is easy to see why so much must be given 
at first. It would appear, then, that in many cases the chief 
effect of manure on our fields consists in this—that in consequence 
of the more abundant nutritives in the upper crust of the field, the 
plants during the first period of their growth push out ten times, 
perhaps a hundred or a thousand times, more root fibres than they 
would have done in poor soil; and that their subsequent growth 
is in proportion to the number of those organs, by means of which 
they are enabled to search for and assimilate the less abundant 
food in the deeper strata. This may explain how a quantity of 
the constituents of manures—ammonia, alkalies, and earthy phos¬ 
phates—so small in proportion to the same matters diffused 
through the soil, increases the fertility in so remarkable a degree.” 
— (Note, Liebig's “ Pam. Letters,” p. 512.) 
And here we may fitly refer again to that last important office 
of carbonic acid to which I alluded briefly at the conclusion of 
my last letter (p. 546) ; and, as in my first letter on humus (p. 472) 
I objected to the interpretation which had been put upon Liebig’s 
theory by S. W. Johnson, I will call the attention of your readers 
particularly to the mode in which Liebig expresses himself, when 
it will be seen that he carefully distinguishes between the insolu¬ 
bility which arises from the natural chemical insolubility of a 
substance and that attractive force which the soil, like charcoal, 
exercises, for example, upon colouring matter, and which “ is 
about on a par with the feeble affinity of water for salts which 
are dissolved by it, but without alteration of their chemical pro¬ 
perties.” The matters attracted “ merely lose their solubility in 
water.” The surface attraction which brings this about is there¬ 
fore termed by Liebig “ physical attraction.” “ In this state of 
physical combination,” he says, “the alimentary substances are 
manifestly in the most favourable condition to serve as the food 
for plants, for it is clear that the roots in all places where they 
are in contact with the soil will find the necessary substances . . . 
retained in the soil by so slight a force that the most trifling dis¬ 
solvent cause brought to bear upon them suffices to effect their 
solution and transference into the plants.” “ The evaporation of 
water from the leaves produces a vacuum within the plant, 
whereby a draught is created which powerfully assists the contact 
of the moist earthy particles with the cell wall (at the extremities 
of the root fibres). The cell and the earth are pressed against 
each other. Between the fluid contents of the cells and the 
nutritive substances physically combined in the earthy particles 
