84 
JOURXAL OF HORTICULTURE AXD COTTAGE GARLEXER. 
[ JaLUiry SO, 1890. 
Then, again, it is only fair to say that gardeners have had little 
help from men of science, who have devoted their researches 
almost as exclusively to agricultural subjects, with the result that 
farmers with any intelligence wmrthy the name are in a position to 
purchase those manures best suited to their land and crops at a very 
reasonable price. We occasionally meet with an unbeliever in the 
efficacy of chemical manures. These are said to be either scourges 
which take every particle of good out of the soil, or they are held 
to burn the crops, and in either case are to be given a wide berth. 
No doubt it is possible that both these things may happen ; but, as 
has been often said, the bad shillings do not prove that every 
shilling is bad, and therefore to be shunned. I think also that it is 
a great mistake to look upon these manures as stimulants, and of 
value merely to give an extra push at a critical period to the 
already hard-worked plant. They may be useful in such cases, but 
such a view does not give a fair representation of their value. A 
good chemical manure is essentially a food, and as such is to be 
made use of in the same way as we apply water—that is, in order 
to meet a felt want. In a certain sense farmyard manures are 
stimulants, for if employed indiscreetly it is found that they 
produce a rushing growth followed by collapse, the principal reason 
for this being the absence of those elements of plant food which are 
or should be present in every carefully prepared chemical manure. 
There is perhaps nothing more difficult to estimate than the 
quantities of such food required by plants. For one thing soils 
differ so much, some holding in sufficient quantity one or other 
of the foods which chemistry is in general obliged to supply. Or 
if applied to a soil its retentiveness may be of so poor a nature 
that a heavy rain may practically destroy the best part of a good 
dressing, while the same rain in the case of soil of a retentive 
character would simply diffuse the manure through the upper 
strata, and make it more available for plant roots. Generally, 
therefore, each cultivator must find out for himself what is best to 
do with his own particular land. In fruit borders and flower 
borders under glass the case is much simplified, and as regards pot 
culture we have the matter practically in our own hands. 
In order to make the remaiks which follow plainer it may be 
indicated that plant nutrition is largely in the hand of Nature, the 
bountiful mother having supplied to a wonderful degree the wants 
of her inanimate children ; but chemists long ago found that a few 
elements were presented in too slight proportions to meet the 
wants of plants when cultivated. None of these entered very 
largely into the composition of plants, but slight as their position is 
they could not be dispensed with, and the plant kept in health and 
vigour at the same time. By means of water culture—that is, 
growing certain plants in water with the addition of some chemical 
elements—German chemists many years ago demonstrated the 
necessity of the presence of in order that plants might perfectly 
fulfil all the functions of their nature. About the same time a 
French chemist was showing that soils—that is, cultivated soils— 
contained sufficient food for plants with the exception of a few 
elements. Thus, Professor Wolff to 1000 parts of water had 
0.S8‘028, and of solid matters Gl'972, or to 94 per cent, of water 
added 6 per cent, of solid matter. In 1000 parts these solids 
were thus proportioned ; — 
Phosphoric acid 
... 82.S4 
Lime 
... 10-370 
Potash ... 
... 912.3 
Magnesia 
... 1-403 
Sulphuric acid ... 
... 2-2.54 
Chloride. 
... 0-88.5 
Nitric aciil 
And one drop of ferric chloride. 
... 29-703 
Other chemists proved that a plant performed all its functions 
properly with a ratio of solids to water of one to over 3000. Ville, 
the French chemist, whose researches have practically revolutionised 
agricultural chemistry, showed that nitrogen, potash, phosphoric 
acid, and lime were the only foods necessary to add to the least 
fertile soils. Instead of water Ville employed calcined sand, and by 
the addition of soda, magnesia, sulphuric acid, chlorine, ferric oxide, 
silica, manganese, nitrogen, phosphoric acid, potash, and lime proved 
that with the addition of water and the carbonic acid derived from 
the air plants performed all their functions perfectly. But Ville 
was a practical chemist, and on a farm where he made experiments 
he found that the soil had in sufficient quantities for the food of 
plants the seven minerals which supply the soda to plants, but 
that nitrogen and the other three must generally be introduced 
by the cultivator. Curiously enough, however, any one of these 
foods may be within reach of plants, but impossibility to assimilate 
the particular food renders its presence of no use—thus the atmo¬ 
sphere is diluted with nitrogen, an element which enters largely into 
the albuminoids of plants, yet only a certain group of plants are 
capable of securing a sufficiency from the air. Very much the 
same remark applies to the mineral agents which may be present in 
soils, but in a form which the plant cannot reduce to a useable 
condition. It will be seen how the base on which plant feeding, 
rests has been simplified. In another paper I hope to have some¬ 
thing to say on the more practical matter of feeding plants.—B. 
Hybrid Dendrobiums. 
The hybrid Orchids raised and sent out within the past ten or 
twelve years have taken prominent positions amongst the most 
beautiful plants in cultivation, and the genus Dendrobium has 
contributed liberally to the list of favourites. At least twenty 
distinct hybrids have flowered and been described, some have been 
illustrated, and a few have been certificated. They all possess some 
special characters of their own, but one remarkable fact must strike 
an observer who has given some attention to these hybrids, and 
that is the regular manner in which the floral form and habit of 
the parents are combined in the seedlings. This occurs even where 
the crosses have been reversed, and the experimental hybridiser 
may fairly expect when he succeeds in effecting a cross that the 
characters of the pollen and seed plants will be nearly equalled 
combined in the offspring, whichever species is made the seed-bear¬ 
ing parent. The leading practical results of hybridising Den¬ 
drobiums have been to increase the diversity of colouring, to impart 
or add to the fragrance, and to prolong the duration of the flowers, 
with, in several cases, greater vigour of habit. 
A brief review of the principal hybrids that have yet flowered 
will illustrate what has been accomplished amongst the Dendro¬ 
biums, and for convenience they may be taken in alphabetical 
order. First, then, is D. Ainsworth! from D. aureum crossed with 
D. nobile, which originated in Dr. Ainsworth’s garden at Lower 
Broughton, near Manchester ; it first flowered in 1874, and was cer¬ 
tificated by the Royal Horticultural Society February 18th of the 
same year. This is one of the best known and most beautiful 
hybrids yet obtained amongst the Dendrobiums either in the 
ordinary form, which has white sepals and petals and rich crimson 
lip, or in the more deeply coloured variety roseum, admirably 
pourtrayed in the first volume of Mr. B. S. Williams’ “ Orchid 
Album ” (t. 20). The lip shows the influence of the two parents, 
for while the form closely resembles that of D. aureum, the colour¬ 
ing is that of D. nobile. The flowers are large, freely produced, 
the plant is of strong habit, and the feathering of the crimson 
blotch on the lip imparts a distinct appearance to the flower, which 
is readily recognised. D. Leechianum and D. splendidissimum come 
very near in characteristics to D. Ainsworthi,and are from the same 
parents. _ 
Several hybrid Dendrobiums are but little known, and amongst 
them we must count D. chlorostele, raised at Burford Lodge, 
between D. Linawianum (moniliforme) and D. Wardianum. It 
has white sepals, petals white at the base, purple at the tip, the 
lip rich purple in the centre, and with a zone of pale yellow, 
the column green. D. chrysodiscus, and its variety oculatum, 
are also Burford Lodge hybrids from D. Ainsworthi and D. 
Findlayanum, the former being the pollen parent. It is distinct, 
but the seed parent’s characters predominate, the lip resembling 
that closely in shape, but differing in colour. The greater portion 
is white, with a dense bronzy red and yellowish blotch at the 
base. The sepals and petals are blush tinted, giving the white 
flow'er a very delicate appearance. The original hybrid was 
certificated by the R.H.S. in February, 1888. The variety 
oculatum has rather more colour in the flowers, and a reverse 
eross has been named melanodiscus. D. Cybele (Findlayanum 
and nobile), one of the Veitchian hybrids, is noteworthy for the 
fact that the pollen parent (nobile) has here had the greatest in¬ 
fluence, the peculiarity of the Findlayanum growth being slightly 
retained, also a little of the lip colouring. D. Dominianum 
(nobile and Linawianum) is interesting historically as presumably 
the first hybrid Dendrobium known, having been raised by Mr. 
Dominy in Messrs. Veitch & Son’s Exeter Nursery. The flowers 
are purple, tinted deeper in the lip, and altogether distinctly of the 
nobile group. _ 
A valuable addition was made when D. endocharis was raised in 
