MISCELLAKEOUS. 
317 
-growing in. a dry, and warm south border, front- 
ing one of the principal plant structures, and 
protected by a lean-to low brick pit, intended for 
minor Cacti. These appear to be the proper occu- 
pants of the border, with an inter-plantation of this 
Oxalis, which upspringing from its dormant con- 
dition on the decline of summer presents in early 
autumn, the unusually charming feature of a bed of 
glowing crimson, contrasted with leaves of a vernal 
greenness ; this, too, at a season when the severe 
frost of a single night, probably, has destroyed 
almost every vestige of floral beauty in the open 
air. Nor is this beautiful appearance exhibited by 
Oxalis Bowiei^ altogether so transient as may at 
first be supposed ; nearly two months ago it was in 
the condition described, in the Society's Garden ; it 
is still fresh and beautiful, and there is a proba- 
bility of its continuing so for a month or six weeks 
to come, through the circumstance of its being 
merely protected from nocturnal frosts and dash- 
ing rains, in the cold structure before alluded to. 
For an in-door display, it is at this season of the 
year also an invaluable plant, and in several places 
we have found it extensively in use, as at Messrs. 
Henderson's in the Edgeware Eoad, &c., and in a 
greenhouse at Wrest Park, the seat of Earl de Grey, 
in Bedfordshire : at the latter place in a luxuriant 
state. At the Horticultural Gardens, in the fine 
collection of orchids, we noticed, among others, 
flowering there, the ever blooming Phalcenopsis 
grandijiora, in a fine state, with numerous long 
branching racemes in difi"erent stages of florescence ; 
the more advanced ones profusely adorned with their 
ample paper-white, yellow-marked blossoms, and a 
beautiful plant of Miltonia Candida is likewise de- 
serving of especial mention, from the number 
of rich brown and auriferous-mottled, white and 
violet-lipped flowers, that were expanded on it. 
Gum Tragacanth. The Common Gum, called 
Tragacanth, brought to us from the Levant, was 
thought by Linnaeus to be produced by the plant 
called Astragalus Tragacantha, a French species, 
called by the Ijotanists of that country A. massili- 
ensis ; but De Candoile assures us, that no gum 
whatever is furnished by that plant. Another 
species, the A. crtticus, has been named as the 
source of the drug, and it does appear that a small 
quantity is obtained from that species in Candia, 
but certainly not the bulk of the samples of Com- 
merce. Labillardi^re relates, that his A . gumviifer 
furnishes Tragacanth on Mount Lebanon ; but the 
samples obtained from thence are said not to be 
the same as those of commerce, being white and 
more transparent, and dissolving less readily in 
water. Finally, Olivier assures us, that the prin- 
cipal part of the Tragacanth used in Europe, comes 
from Astragalus verus, a Persian species. The 
only certain conclusion that can be drawn from 
these statesments is, that Tragacanth is a secretion 
from some sort of Astragalus belonging to that 
curious division of the genus, which consists of 
spiny bushes. The subject has been very recently 
investigated by James I3rant, Esq., Her Majesty's 
Consul at Erzeroum, who has sent excellent dried 
specimens of the Tragacanth plants of Koordistan, 
to the Hon. W. F. Strangways, One of these is 
labelled " The shrub that yields the white or best 
variety of Gum Tragacanth," and is the Astragalus 
gummifer, a very pretty bush, unknown in the 
gardens of Europe, and very much to be desired 
as an ornamental plant. For it is covered with my- 
riads of short spikes of yellow flowers, embedded in 
wool, and surrounded by bright green smooth leaves. 
Mr. Brant's other Tragacanth is labelled, " Shrub 
from which the red or inferior species of Gum 
Tragacanth is produced " This is quite a different 
plant, with hoary spiny leaves, and little cone-like 
heads of flowers, whose feathery calyxes are as long 
as the corollas. It is evidently very near the 
A. 7mcrocephalus of Willdenow. Hence it appears 
that the best Tragacanth is really furnished by 
A . gummifer, as Labillardi^re affirmed ; that no 
additional evidence as to the accuracy of Olivier's 
statement concerning A . verus, has been obtained ; 
but the existence of a third Tragacanth plant has 
been clearly ascertained, which has been named 
A. strohiliferus. Lindley, in Bot. Beg., v. 26, p. 
38, Miscell. 
On the Motion of Gum in Plants. In his 
investigation of the anatomy of Cycadacece, Pro- 
fessor Morren has arrived at a fact of great interest 
in Vegetable Physiology. It is well known that 
all these plants yield an abundance of gum, which 
flows from them freely in a liquid state when 
wounded ; and that the flow of such matter takes 
place in special channels, namely, in long fistulas, 
whose walls are built up of cellular tissue. It is 
usually supposed the Gum is a secretion from the 
leaves of plants, and that it consequently flows 
from above downwards : it has been even compared 
to the blood, and regarded as the most pure, and 
most essential part of their nutritive matter. Pro- 
fessor Morren has, however, proved by some well- 
conducted experiments, that in Cycadaceae at least 
the gum moves from below upwards, and that it 
arises in the stem, where it mounts into the leaves. 
The author, therefore, suspected that gum is an 
ulterior ^elaboration, excited, or brought about, or 
at least assisted by some acid, probably supplied 
by the leaves themselves to the trunk ; a suspicion 
eventually confirmed by chemical investigation. 
M. de Coninck, Professor of Chemistry at Li^ge, 
analysed the leaves of Cycas i^evoluta, and ascer- 
tained that they contained 1° chlorohydricacid, pro- 
bably combined with soda or potash; 2" Oxalic acid, 
probably free ; and 3° oxalate of lime, forming the 
principal part of the solid exterior layer of the 
leaves — a very interesting fact, inasmuch as super- 
ficial indurations of plants have always hitherto 
been ascribed to the presence of silex. From these 
facts, M. Morren concludes, that in Cycadacece, 
gum is formed at the expense of the starch of the 
stem, and that such a change is efiected by the 
action of the free oxalic acid secreted in the leaves. 
We are, therefore, to understand that Gum is a 
form of the nutritive matter of plants ; that, in- 
stead of being the result of vegetable digestion, it 
is a principle created by Nature for their crude 
food ; that one, at least, if not the principal of the 
functional purposes for which starch is universally 
dispersed through the tissue of plants, is in order 
that it may be everywhere ready for conversion 
into gum : and finally, that it is in the form of gum 
that starch passes through the sides of the tissue 
