132 
THE FLORIST AND POMOLOGIST. 
foliage, as "well as ordinary plants. The ex¬ 
periment might he prolonged as long as de¬ 
sirable, and, probably, unlooked-for results 
would occur as to the form or colour of the 
organs, particularly the leaves. 
Permit me to recall on this subject an ex¬ 
periment made in 1853 by Professor Yon 
Martius.* It will interest horticulturists 
now that plants with coloured foliage are 
becoming more and more fashionable. M. 
Yon Martius placed some plants of Amaran- 
thus tricolor for two months under glasses of 
various colours. Under the yellow glass the 
varied tints of the leaves were all preserved. 
The red glass rather impeded the develop¬ 
ment of the leaves, and produced, at the base 
of the limb, yellow instead of green ; in the 
middle of the upper surface, yellow instead 
of reddish-brown ; and below, a red spot 
instead of purplish-red. With the blue 
glasses, which allowed some green and yel¬ 
low to pass, that which was red or yellow 
in the leaf had spread, so that there only 
remained a green border or edge. Under the 
nearly pure violet glasses, the foliage became 
almost uniformly green. Thus, by means of 
coloured glasses, provided they are not yellow, 
horticulturists may hope to obtain at least 
temporary effects, as to the colouring of va¬ 
riegated foliage. 
The action of electricity on vegetation is 
so doubtful, so difficult to experiment upon, 
that I dare hardly mention it; but it can 
easily be understood how a building con¬ 
structed as proposed might facilitate experi¬ 
ments on this subject. Respecting the action 
of plants on the surrounding air, and the 
influence of a certain composition of the at¬ 
mosphere upon vegetation, there would be 
by these means a large field open for experi¬ 
ments. Nothing would be easier than to 
create in the experimental hothouse an at¬ 
mosphere charged with noxious gas, and to 
ascertain the exact degree of its action by 
day and by night. An atmosphere of car¬ 
bonic acid gas might also be created, such as 
is supposed to have existed in the coal period. 
Then it might be seen to what extent our 
present vegetation would take an excess of 
carbon from the air, and if its general exist¬ 
ence were inconvenienced by it. Then might 
be ascertained what tribes of plants could 
bear this condition, and what other families 
could not have existed, supposing the air had 
formerly had a very large proportion of car¬ 
bonic acid gas. 
Until horticulture can supply physiology 
with such convenient means of experiment, 
it, in the meantime, advances descriptive bo¬ 
tany by the valuable publications it issues. 
The greater part of the old works with plates, 
such as “ Hortus Eystettensis,” “ Hortus 
Elthamensis,” &c.; also those of Yentenat, 
Cels, Redoute, &c. ; the “Salictum” and 
“Pinetum” of the Duke of Bedford; and, 
more recently, the “ Rhododendrons of the 
Himalaya,” by Dr. Hooker; the works of 
Bateman, Pescatore, Reichenbach, on Or¬ 
chids ; and many others I could name, would 
never have been published had there not been 
rich amateurs either to edit or to buy them. 
It is horticulture that has given us the 
longest series of illustrated journals that 
have ever been published; and here I must 
do justice especially to the English horticul¬ 
turists. No doubt the science of our time 
requires a larger amount of analytical de¬ 
tails than is contained in the plates of the 
“ Botanical Magazine,” “Botanical Register,” 
“Andrews’ Repository,” “ Loddige’s Botani¬ 
cal Cabinet,” “ Sweet’s British Flower Gar¬ 
den,” “ Paxton’s Magazine and Flower 
Garden,” and other English journals; but 
what a number of forms are thus fixed by 
the engravings in these books, and what a 
fund of valuable documents for consultation 
they afford ! One cannot fail to admire the 
“Botanical Magazine,” commenced in 1793, 
continued from month to month with an ex¬ 
emplary regularity, and which is now at its 
5580th plate. Not only has it always repre¬ 
sented rare and new species, but it has ever 
been conducted on a simple and uniform plan, 
which renders it convenient to consult. 
The series of plates is unique from the 
very beginning. Each plate has its number, 
and each article of letter-press refers only to 
one plate, by which means the quotations 
from the work are rendered brief and clear. 
Many editors have not understood the advan¬ 
tage of this simple arrangement. They have 
varied their titles, their series, their pagings; 
they have affixed to their plates numbers, 
then letters, then nothing at all; the end of 
which is (and this ought to serve as a warn¬ 
ing for the future'), that the more they have 
altered and complicated the form of their 
journals, the shorter time they have lasted. 
How is it that these purely bibliographical 
details cause in us such sad recollections ? 
Of the men just mentioned, who have ren¬ 
dered such eminent service to botany and 
horticulture, England has lost three during 
the year 1865—Sir Joseph Paxton, Dr. Lind- 
ley, and Sir William Jackson Hooker.* I 
should certainly fail in what is expected of 
me if I did not express, in the name of the 
foreigners attending this meeting, our deep 
regret at such serious losses. We know them 
all by their writings, and many amongst us 
have known personally the distinguished men 
I have mentioned. Their names follow us at 
each step in this the scene of their labours. 
If we admire the boldness of construction 
* Since these lines were in the printer’s hand 
British science has sustained a severe loss in the 
death of the truly amiable and learned Professor 
W. Harvey, of Dublin, so well known by his works on 
Algal, and on the Botany of South Africa. I cannot 
refrain from expressing our sense of this great be¬ 
reavement. 
* “ Gelehrte Anzeige,” Munchen, 2 Dec., 1853. 
