52—1846.] 
THE GARDENERS’ CHRONICLE. 
en ame 
851 
ORTICULTURAL SOCIETY OF LONDON.— 
Notice is hereby given, that the EXHIBITION OF 
FLOWERS AND FRUIT, at the Society’s Garden, in the 
ensuing season, will take place on the following Saturdays, 
j: 17 ; and that Tuesday, April 20, 
SATURDAY, DECEMBER 26, 1846. 
MEETINGS FOR-THE.TWO FOLLOWING WEEKS. 
RIDAY, an, 1—Botanical H b . 8PM. 
4=Entomological 
ONDAY, = + 8 PM. 
AN ingenious invention, which appears: likely to 
be of great value to those who grow Prants IN 
their srrrinc-rcoms, has lately been brought under 
our notice. It is well known that in such situations 
plants suffer principally from the dryness to which 
their roots are necessarily exposed, in addition to 
the evils of a fluctuating temperature in the soil— 
as a remedy for which double-sided pots, slate pots, 
and other such methods have been proposed, None 
of them have, however, a right to say that they 
fully answer the purpose ; they are all imperfect 
attempts at improvement, and one of the best proofs 
of their not entirely answering the purpose is, that 
they are so little used. 
The invention to which we would now draw 
attention seems to be a really effectual apparatus, 
or so we must designate it. Let the reader ima- 
gine a metal case, open upwards, closed below, ex- 
Cept at an aperture for the escape of surplus water ; 
let this case be furnished with a moveable stand, 
whieh can be taken out at pleasure, together with 
a garden pot, for receiving which it is intended ; 
suppose this stand, with its garden pot, introduced 
into the metal case, and the upper part, pre- 
viously open, closed by two other plates of 
metal, and some idea may be had of the sim- 
plicity and general nature of the contrivance. It 
will be obvious, if we have made ourselves under- 
stood, that when a garden pot is introduced into 
the case, and the upper part is covered in by the 
two moveable lids, any water which may be poured 
into the case will rise in the form of vapour, and 
keep the sides of the pot in à uniform state of mois- 
ture, without much variation of temperature. The 
roots ofthe plants will, in fact, thus find themselves 
ina hollow case always equally damp. This is pre- 
cisely what is wanted, and all that is wanted, to 
preserve plants in health in sitting-rooms, provided 
they are also kept clean and near the light. 
We have not seen the apparatus in action, 
although we soon shall make ourselves personally 
better acquainted with it ; but we are assured’ that 
it answers perfectly. Mr. Parries, a very inge- 
nious and philosophical gentleman, who hit upon 
the contrivance, states that “if a Pelargonium or 
Fuchsia in bud be placed in the apparatus, and 
another plant of the same kind somewhat its supe- 
rior be treated by the ordinary method, and the 
flowers and foliage of both are d after the 
servants. But no such loss. will be sustained if the 
interior of the apparatus is kept damp merely by 
vapour suspended in the phere which the case 
contains ; an abundance of water will, wessuppose, be 
supplied bythat vapour. At all events the plan we 
propose would obviate much of the necessity’ of 
watering. 
But we must refer the reader for further details 
to the pamphlet and apparatus, which we feel sure 
will amply reward him for the small sum it may cost 
to procure the latter. ‘The pamphlet is full of good 
sense, and to the principles it inculcates we see no 
reason to object, except so far as the importance of 
porous pots isinsisted upon» No'doubt they must be 
porousfor Mr. Pariures’s apparatus, but porosity 
is no-advantage in general—rather the reverse. 
We may as well add that this apparatus is neat 
and ornamental, as well as useful. In fact it is got 
up in various ways to suit the taste and pocket of|; 
buyers. 
THE POTATO DISEASE AND THE APHIS 
VASTATOR OF SMEE. 
In Smee’s work on the Potato plant it is stated that 
an Aphis is the ‘cause of the disease that has recently 
appeared with so much virulence, and that the same 
insect has attacked the Spinach, Turnip, Carrot, and 
numerous other plants as well. The alarming account 
which Mr. Smee has given of the destructive ravages of 
the Aphis, that he has described in his work as the 
vastator (248, 274, 275, 276, 294, 332, and 462), its 
wonderful fecundity (267, 268), and the threatened con- 
sequences to the human species of death by famine to 
the amount of millions (404, 462, 522), has induced 
me to study the character of the creature from which, 
according to Mr. Smee, man has so much to apprehend 
bably.lead to a better. understanding its character 
and uses in the economy of nature than those assigned 
to it by Mr. Smee, 
In one of the Spinach’ plants that I examined, the 
central leaves were covered with a minute fungus, the 
head! of which was globular, This’ head was attached 
to a footstalk, which was about equal in length to two 
diameters of the:head of the fungus. The footstalk was 
a:simple tube, formed of a membrane peculiar to many 
kinds of fungi that I am acquainted with—the Boleti, 
Botrytis; and others of that class; and it stood erect 
from the leaf, so that at fivst sight the stem was seldom 
perceived, and indeed might have been easily overlooked 
in a cursory examination,and the head mistaken for 
the ovary of some insect, which at first sight I believed 
it to be, especially as-I found nearly three-fourths of the 
eads broken and emptied of their contents. After I had 
Satisfied my mind as to the character of these fungi, I 
selected one:of the leaves that was completely covered 
with them, and: which contained two Aphis vastators 
eeding; I watched one Aphis very closely, and ob- 
served its- actions: minutely ; following it with the mi- 
eroseope through all its- wanderings for some time, 
when'atlength I observed it seize one of the heads of 
the fungi and empty itof its contents. This cireum- 
stance opened a new field of thought as to the probable 
office of the Aphis; and its uses in the order of Nature, 
and I pursued the inquiry further, for the purpose of 
eliciting other proofs of the same kind: In the exami-. 
nation, however, that I refer to, I only succeeded in 
procuring a’ partial confirmation of the fact, inan Aphis 
seizing a head, which I could not detect that it emptied. 
The fact of the number of Heads of fungi broken and 
emptied: of their contents, and that of the Aphis empty- 
ing one, incline me: to believe that the office of the 
Aphis has a relation to fungoid matter, and the relief 
of vegetation fromi their external action; as from con- 
The Aphis vastator, then, according to Mr. Smee, is 
the cause of the Potato disease. It has attacked the 
Spinach and diseased that also, and numerous other 
plants as well. My present business, however, is with 
the Potato and Spinach ; and I intend to see how far 
facts warrant the conclusion of Mr. Smee as to the 
office and power of the Aphis in connection with the 
disease of those plants; and as I apprehend that Mr. 
Smee is, like myself, an enquirer after truth wherever 
it may be found, I am sure he will rather rejoice in my 
attempt to discover it, than consider the inquiry on my 
part either invidious or unfriendly. 
For the purposes of this inquiry I have carefully and 
minutely examined several plants from a crop of 
Spinach, the produce of seed sown in August: last, and 
which were all more or less diseased ; I have also ex- 
amined plants the produce of seed later sown, and in 
which no disease atthe present could be detected by 
the naked eye. lu the-first crop the Aphis vastator of 
Smee exists; in the second, none could be found. 
Finding the Aphis on the leaves of the first crop, I 
dertook a ‘lengthened mi pieal eae 
the insect, its mode of feeding, what it appeared to feed 
on, and the condition of the vessels of the roots, stems, 
and leaves of the plant in- which it was found. 
results of these various examinations I-will'now state. 
The drawing in Smee’s work of the- Aphis*vastator 
corresponded with the Aphis I found, excepting the 
proboscis, which I examined under a power of 480 
p i 
lapse of some days, a remarkable difference in their 
beauty will be seen ; and so perceptible will this be, 
that the most inexperienced eye will detectit.^ He 
adds that ** many experiments have been made upon 
Pelargoniums, Fuchsias, Polyanthuses, and other 
plants with the apparatus, and. the results, without 
one exception, were all of the most satisfactory cha- 
racter, We have no doubt of the accuracy of this 
Statement, firstly, because we know Mr, PHILLIPS, 
and can answer for his good faith, and secondly, 
because it is just what we should have expected 
under the circumstances. Mr. Pmirries has, in 
fact, proceeded upon strietly philosophical princi- 
ples, and of course has obtained a result which 
might have been foreseen. 
e have not at present the space required for 
going into a detailed examination of all the points 
that. suggest themselves in reading over the pam- 
phlet which is given away with this apparatus ; * 
nor,indeed, is it necessary. For it, like all other 
contrivances,will require different treatment accord- 
ing to seasons and the plants which it receives. We 
would, however, suggest one thing—namely, that 
instead of watering the soil in which a plant is 
growing,it would be quite sufficient to introduce 
Some wet sponge into the cavity between the flower- 
pot and its metal case, keeping that sponge moist. 
One of the greatest difficulties with plants in pots 
Consists in the continual abstraction from: their soil 
of the soluble matters which it contains, and this 
deteriorating aetion will of course be greater in 
sitting-rooms than anywhere else, partly on account 
of the necessity of large supplies af waist order to 
compensate for the quick evaporation that is always 
Eoing on there, and in part because of the little 
Skill that is shown in gardening by mere domestic 
* Phüllips's Plant and Flower Improver ; an elegant and pleasing 
apparatus for improving the growth of plants and flowers, |. S. 
Broady, Halkin-street, 
with the usual compound arrangement. 
The proboscis: of the vastator appeared to me to be 
a tube within a sheath, and not formed of three 
pieces, as described by Smee. In all other respects, 
however, the insect agreed with Smee's deseription, 
and I have, therefore, no doubt of its identity. Its 
solitary habits, its mode of attachment to the leaf, and 
general characteristics were as laid down by Smee. 
Having satisfied myself of the identity of the Aphis, 
I patiently studied its feeding, in order to ascertain its 
effect on the leaf. To do this advantageously, I se- 
lected a portion of a leaf on which an Aphis was feeding, 
and brought the proboscis of jthe insect, by placing its 
head opposite to the object glass, within the field of 
vision, Thus arranged, with an object glass of 125 
d nd 
to be named, I deem the Aphis 
ineapable of injuring amy other vegetable life than 
than that of a; parasite similar to-what I have already 
named. 3 
As'the action of the Aphis: on the leaf of a plant, 
neither punctures nor discolours the cuticle in any way 
that is perceivable, it cannot injure either the external 
tissues or internal organs, It is, therefore, difficult to 
perceive in what way the abstraction of the juices of a 
plant, admitting this to be so for the moment, of which 
however we require proof, causes a disease of the ves- 
sels, as in-the case of the-Potato and Spinach. I have 
examined several plants of Spinach microscopically 
from the roots upwards, and in all of the diseased ones 
I found globular and stellate fungi. In the leaves also 
of some plants, which appeared perfect to the eye, and 
on which no Aphis or external fungi could be found, I 
have discovered the globular fungi in the vessels of the 
leaf-stalk. In all these cases the fungi may be traced 
from the root upwards, and they diminish in intensity 
as we approach the leaf. The origin of the fungi in the 
Spinach is. clearly at the base or root, as was the case 
with the Potato, and'as it is found in the vessels of the 
plant before either external fungi or Aphis appear, we 
have facts that bespeak an abnormal or unhealthy con- 
dition of the plant before the Aphis is:seen. As the 
fungi, therefore, precede the Aphis, the Aphis cannot 
be the cause of their appearance; and as fungi can- 
not sensibly exist in plants without disturbing - their 
functions, the: unhealthy condition of the Spinach and 
Potato is not referable to the Aphis. But beyond these 
facts, the formation of the Aphis forbids the idea of its 
being destructive of healthy vegetable life. Its simple 
proboscis that-does not penetrate the cuticle of the leaf 
it inhabits is all the means the insect possesses to com- 
mit the dreadful ravages Mr. Smee attributes to it; 
the diameter of which does not exceed soyo of 
an inch. How insignificant is this tube compared with 
the jaws ef a- caterpillar, which in power and capability 
isa very Behemoth to the poor little roving Aphis ; and 
yet the caterpillar, with all its powers, has never 
been. so heavily taxed as the Aphis vastator. An 
Observation which Mr. Smee has made would, if he 
had followed. it up, have led, as I believe, into the right 
path, and: induced him to have arrived at a different 
diameters, in a powerful p pp aj 
with a very brilliant light concentrated on the point of 
the proboscis of the insect and the part of the leaf to 
which it was attached, I awaited its liberation from 
feeding to ascertain its effect on the leaf. During the 
action of feeding no motion of the proboscis was per- 
ceptible, and the body of the insect was so quiescent, 
that in one instance I thought the creature was dead ; 
after a lapse of 20 minutes, however, in this case, the 
insect removed its proboseis, and on its removal I mi- 
nutely examined the spot from which it had been taken. 
No puncture of the cuticle or any discoloration or dis- 
organisation of that part of the leaf was observable, 
and I could discover no difference in the texture from 
that of the parts immediately surrounding it. I re- 
peated this experiment five or six times, with other in- 
sects, on different leaves, and with precisely the same 
results, The cuticle was uninjured and no discolora- 
tion observable. The cuticle of the Spinach is formed 
of minute tubes, “overlaying a membrane ; these tubes 
are arranged angularly, and between these, it was ob- 
served, the Aphis thrust its proboscis. ‘The. insertion 
of the proboscis extended only superficially inwards 
among the tubes, as I could observe the point of it 
uring the whole time of its feeding. I have now to 
relate a discovery, which requires, I admit, further 
confirmation before it can be said to determine the pre- 
cise office of. the Aphis, but which, I think, may pro- 
with regard to the Aphis than the one he 
has promulgated. Mr. Smee states, p. 86 (267), “The 
Aphis vastator comes upon the Potato plant in the winged 
state, and there brings forth its young alive. These ge- 
nerally prefer at firsta large and rather debilitated leaf.” 
at isa debilitated leaf but a diseased one? And 
why do the vastators prefer diseased leaves if they are 
destructive of healthy life t 
These queries are answered at p. 90 (286), and at 
~ 
f 
[zi 
[5 
286). * The vastator does not commit the same 
amount of mischief on every kind of Potato. / dis- 
likes those. leaves where moisture is to be found on the 
under surfaces àn the morning, and thus, according to 
the state of the plant, it passes over with greater or less 
rapidity.” 
(451). * There is an exquisite relation existing be- 
tween the effects: upon tlie plant.and the welfare of the 
animal. This creature cannot well live upon avery 
vigorous plant, because it would be drowned by the water 
transpired at night. Hence it generally commences upon 
leaves whichhave in agreat degree lost their vigour. On 
placing insects wpon the new leaves of very vigorous 
plants, I have observed that the creature has always 
been obliged to leave them. It commences upon the larger 
and nearly exhausted leaves ; from these it passes to 
others, and soon till the entire foliage is affected. 
Now what is. this but simply saying that the Aphis- 
