April 25th, 1885. 
THE GARDENING WORLD, 
533 
bright blue flowers of the lovely Anemone apennina 
are also expanding, as well as the superb A. fulgens. 
In the herbaceous border we noted the following, 
and several of them were also represented on the 
rockwork : the two Lung-worts, Pulmonaria sacchara- 
tum and P. mollis, are just expanding. The former 
has leaves prettily blotched with whitish-green and 
purplish-blue flowers ; the latter has almost unspotted 
leaves and flowers of a claret-purple shade. 
Pew things at this time present a showier 
appearance than Doronicum austriacUm, several 
clumps of which are clothed with their brilliant 
golden blossoms. Arnebia echioides is closely 
allied to the Lung-worts, but has yellow flowers. 
It is a handsome plant, but seems to prefer a sheltered 
nook on the rockwork. A pretty little plant not 
often met with is Isatis japonica, a first cousin of the 
Woad, the latter of which is celebrated as producing a 
blue dye with which the Ancient Britons are said to 
have ornamented their bodies. The Japanese repre¬ 
sentative has bright green pinnatifid leaves and yellow 
flowers, and grows 6 ins. high. 
A few showy bulbs maybe mentioned in conclusion: 
Chionodoxa nana is a second species of a genus which 
has become decidedly popular of late years. It differs 
from C. Lucili® in being dwarfer and later, as well 
as in having smaller flowers; it is nevertheless very 
pretty. Puschkinia scilloides is 6 ins. high and 
produces dense racemes of white flowers. Muscari 
botryoides, the deep blue Grape Hyacinth, is a well- 
known and handsome plant, which is flowering in 
abundance, and we mention it to call attention to 
the variety pallens. This is a very pleasing plant, 
differing from the species in having flowers of a very 
pale azure-blue, and producing a very pretty contrast. 
The whole of the foregoing, as well as numerous 
others not here mentioned, are well worthy of culti¬ 
vation.— X. 
——- 
FORMS OF LEAVES, 
At the fortnightly meeting of the Linnean Society, 
held on Thursday evening, April 16th, a paper was 
read by Sir John Lubbock, M.P., on the “Forms of 
Leaves.” Though somewhat on the lines of a former 
lecture, the question chiefly considered was some 
causes which might possibly have operated in modify¬ 
ing the form of leaf from the ancestral type. After 
pointing out the prevalence of the palmately-lobed 
form of leaf, he showed by a series of beautifully 
executed drawings that many plants with lobed leaves 
produced more or less cordate leaves when in the 
seedling state, thus indicating that the cordate form 
was prevalent in the ancestral type, but had been 
departed from through some advantage gained by the 
lobed type. 
After pointing out various possible causes which 
had occurred to him, but each of which had in turn 
to be dismissed, he was inclined to think the cause 
was a purely mechanical one. He showed by a 
model how this might take place. Two leaves, a 
cordate and a lobed one, were cut out of cardboard, 
and being suspended by a thread to either end of a 
horizontal bar were shown to be of equal weight, and 
consequently of equal surface. They were then fixed 
on by their bases as if growing, and the cordate leaf 
at once overbalanced the lobed one a little. This arose 
from the centre of gravity in the former being further 
horn the centre of the bar. Two equal weights -were 
then placed on the respective centres of each leaf, and 
the effect was still more pronounced. Hence a lobed 
leaf of the same extent was better able to resist the 
pressure of the wind. 
In a lobed leaf the arrangement of the nerves was 
different to that seen in a cordate one. The sap which 
fed and produced the lamina of the leaf passed chiefly 
along these nerves of vascular tissue,—which was 
illustrated by some Chinese Primula leaves, which 
had been placed in red ink. The sap took the 
shortest cut to arrive at its destination, and in this 
way, certain of the small nerves would become en¬ 
larged, and ultimately the palmate arrangement of the 
nerves would be developed. Some leaf peculiarities 
had been attributed to chemical causes, but he inclined 
to think a mechanical cause was the more correct one. 
Short-leaved species of Pines usually retained their 
leaves much longer than long-leaved species, some of 
the former from five to eight years, or even more, 
while the latter often shed them when two or three 
years old. The Larch was a curious departure from 
the typical habit, but it generally grew in variable 
climates, where the extremes of cold and heat in 
summer and winter were rather great, and it had pro¬ 
bably found it beneficial to cast off its leaves at the end 
of the period of growth, and produce new ones in the 
following spring. Numerous other peculiarities were 
commented upon, and Sir John believed that all the 
peculiarities of leaf character were the result of some 
definite cause. 
LiELIA ANCEPS VARIETIES. 
Ljelia anceps Dawsoni. — This grand variety 
has the honour of being one of the most beautiful 
and at the same time the most highly prized 
of the varieties of L. anceps, as well as of being 
the first white form introduced. Indeed, since the 
introduction of the typical L. anceps, which flowered 
■with Messrs. Loddiges in December, 1835, no other 
variety of note w T as introduced, except the highly 
coloured L. a. Barkeriana, until this strikingly hand¬ 
some variety flowered in the collection of T. Daw r son, 
Esq., at Meadow-bank, near Glasgow, in 1867. It is 
perhaps the best shaped of any of the varieties. The 
sepals and petals are pure white, lateral lobes of the 
lip white, with purple lines radiating from the base, 
L.ELIA .ANCEPS DAWSONI. 
and clear yellow marking in the upper portion. The 
low T er half of the lip, which is wavy, is -white towards 
the lobes, and purple at the extremity. In fact, the 
lip presents to the eye a good body of bright purple 
colour, which contrasts remarkably with the pure 
white sepals and petals behind it. All who have the 
true Dawsoni should carefully nurse it, for it is a real 
gem. 
ON DESTROYING INSECTS. 
(Concluded fromp. 526.) 
Red-spidee seldom attacks Vines or plants if due 
care is taken to give liberal treatment to the roots and 
due attention is observed as regards supplying moisture 
in the atmosphere. Above the hot-water pipes and 
in very light houses, and also when Vines are 
heavily cropped, this troublesome pest will often make 
its appearance, first of all on the small and weakly 
foliage, near where the evil is most felt, and when 
discovered no time should be lost in applying a 
remedy. If the pest is seen almost at its first appear¬ 
ance, that is, before many leaves are affected, the 
simplest plan is to sponge them, if syringing them 
is not practicable, otherwise the latter is the simplest 
plan. The water should be applied with as much 
force as is safe without breaking the leaves to pieces, 
and if a small handful of sulphur is first damped and 
well mixed with about four gallons of water it will be 
found to materially keep this insect in check, but this 
should not be applied to tender foliage. 
It is not at all uncommon for this insect to make its 
appearance in vineries about the time the colouring 
process is going on, or by the time that it is completed. 
The simplest way to settle it in this case is to paint 
the hot-water pipes with a mixture of water and 
sulphur, either when the pipes are warm or at a time 
when the heat may be put on after the sun is off the 
house. The water in the pipes should be heated to 
nearly boiling heat, after which it may be allowed to 
subside gradually, so as to be quite cool by the time 
the suh’s rays are upon the house again, and great 
care should also be taken that the ventilators are 
opened extra wide before that time. The heating 
process should go on two or three times, at intervals 
of a few days. 
Partial shade and the application of the syringe 
Works wonders in keeping this pest in check. I do 
not think it is going too far to say that when this pest 
appears it shows that there is some fault in the 
management, either the plant is dry at the root, in 
too much heat, or starved, overcropped with fruit, 
ovei-heating of the hot-water pipes, insufficient 
moisture in the atmosphere, or the want of a little 
shading, which becomes necessary even for the most 
sun-loving plants under the large squares of clear- 
glass in many of our modern-built houses. 
Scale, of which there are several kinds, are very 
troublesome pests, especially the white one, and 
where it once gets a footing it is a very troublesome 
thing to thoroughly eradicate. A very strong solution 
of soft soap or Gishurst Compound, 2 ozs. to 4 ozs. to 
the gallon of water, with a wine-glassful of paraffine 
oil added to each gallon of the mixture, may be used 
with a sponge on some plants, and the best time to 
use it is while they are not making their growth, 
For the hard stems of Camellias, Ixoras, and the 
like, a hard brush may be used instead of a sponge. 
In the case of tender foliage the mixture should 
not be nearly so strong, and rather a hard piece of 
sponge is the best for use, with the addition of a small 
brush made by cutting a bunch of hairs out of any 
old broom and tying them on the end of a small stick 
about 3 ins. long, the other end of which should be 
a little pointed. This will greatly assist in removing 
the pest from all nooks and corners where the sponge 
will not act, and the small brush will be found very 
useful for removing them from the small stems, 
Scale on Peach trees, and those on Plum trees, can 
only be dealt with in the winter season, at which 
time all insect pests should be got thoroughly under, 
Mealy-bug is one of the most troublesome pests 
■with which the cultivator of hothouse plants has td 
contend. When plants become infested with this 
pest it becomes a constant source of anxiety to keep 
the plants at all presentable. I have heard of people 
thoroughly ridding their place of this pest, and I 
myself have not the slightest doubt but that it may be 
done, but although I have not succeeded yet I live in 
hopes of doing so some day. I am convinced, after 
working at this pest on and off in different situations 
for nearly twenty years, that to rid ourselves thoroughly 
of it cannot be brought about by the usual method 
of dealing with it; that is, to let it alone till it gets 
bad, and then give what we think a thorough clean* 
ing with either soft soap or Gishurst Compound, at 
the rate of 2 ozs, to 4 ozs. to the gallon of water, 
sponging all infested plants from bottom to top, after 
which they are often left alone perhaps for a week or 
two before being examined again. 
I have attempted to rid plants of mealy-bug by 
means of paraffine and water at the rate of 4 ozs. to a 
four-gallon can of water, and have also used the same 
with soap added, and this mixture has been used 
freely among such plants as Gardenia, Stephanotis, 
Ixora, Tabennemontana, and Franciscea, for two 
years. It certainly kept the pest in check and 
did the plants no harm; but I do not believe 
that I should thoroughly eradicate this pest by 
means of the syringe and the above mixture in a 
lifetime, ow-ing to their concealing themselves in 
positions where the syringe does not play directly upon 
them. Besides, many of the insects are knocked down, 
and if left to crawl about in all directions, they spread 
again rather than are destroyed. I know that plants 
which are subjected to frequent syringings with the 
above mixture never get very badly infested, and may 
be kept passably clean by that means, but to thoroughly 
annihilate the pest the plants would have to be carried 
outside and turned over, so as to bring the mixture to 
