78 
of the Tamarisk ; and, if eaten in quantity, is said to be purgative. The Arabs eat it with bread, as they 
do honey, wliich it resembles in sweetness, having an agreeable aromatic flavour. It has been supposed 
to result fi'om the punetui'e of an insect of the coccus family. But this mann by no means answers to all 
the statements respecting the manna — which we understand to have been altogether a miraculous 
production : it was certainly so as to its continued supply, if not also as regards the substance itself. 
It is described as white, lOve hoar-frost f as round, and of the size of coriander seed ; as falling with 
the dew every morning — a double quantity falling every sixth day ; as becoming corrupt and breeding 
worms, if kept till the second day, except on the Sabbath ; as being kneeded into dough, and baked 
into cakes ; as tasting like wafers made with honey ; and as suddenly ceasing its supply on the morrow 
after the people " did eat of the old corn of the land," — " neither had the children of Israel manna any 
more" (Josh. v. 12). Many of these particulars do not apply to the 7?iann ; and, on the whole, it may 
be doubted whether the gummy exudation of the Tamarisk, or of any other tree, — for several have 
been suggested, — had anything to do with the daily food of the Israelites duiing the years of their 
wanderings. — M. 
Eraim. 
Aspects of Nature in different Lands and different Climates, 
loith Scientific Elucidations. By A. Von Humboldt, 
Translated by Mrs. Sabiue. London, Longman and 
Miuray. 2 vols. 
(second notice.) 
In the Essay on the "Physiognomy of Plants," the 
author commences with a very graphic sketch of the 
disti'ibution of organic life over the globe. Not only 
have the declivities of the highest mountains their ap- 
pointed inhabitants, but the ocean, even the atmosphere, 
are filled with hving things, cither perfect creatui'es, 
or the germs of others, borne about by cun-ents to find a 
new home far from then- native spots. Some animals 
venture even to take up their abode in ice. The vege- 
table kingdom presents remarkable difi'erences according 
to the physical position in which its members are placed, 
and still more strictly marked than in the animal king- 
dom is the peculiarity of the vegetable world in each 
particular zone. At all events, the peculiarities of ve- 
getation are much more remarkable than those of the 
animal kingdom, so far as relates to the general impres- 
sion produced ; animals are small in proportion, are 
endowed with motion, and frequently withdi'aw them- 
selves from the eye of man ; whUe plants, fixed objects, 
by then- size and the vast spaces they cover by their 
accumulated numbers, form the most striking feature of 
the landscape in all but the most ban-en regions. 
The eye is gladdened in a temperate and well-wa- 
tered disti-iet, by the cheerful carpet of turf, unknown 
in hotter climates, where the grasses grow in ranker 
development, in isolated tufts, or even, as the bamboo, 
become arborescent, while the delicate, tender herbs are 
exchanged for half-woody shi'ubs or taller herbs, in 
either case for plants incapable of being reduced to the 
soft uniform growth of our pastures. Under a hotter 
sun the scene changes in a way dependent chiefly upon 
the position of a region in regard to the cm-rents of au- 
and \'icinity of moimtains, since, on the one hand, the 
bm-ning heat may draw forth that prodigious luxuriance 
of vegetation which is met with in the well-watered 
regions of South America, on the east side of the Andes ; 
while, should the watery vapour be absent from the winds 
blowing over the region, as in some places on the west 
side of the Andes, and over the central tracts of Northern 
Africa, vegetation perishes from the parching drought. 
Passing from the general -views, the author aelectg 
certain remarkable types, as representing the forms 
giving the most striking features to the scenery of dif- 
ferent parts of the globe, and concludes -with some re- 
flections on the pleasure to be derived by the contem- 
plation of their grouping, and the great field that lies 
open to landscape painters, in the study of the vegetable 
forms of warmer regions in their native countries. This 
last consideration is one that deserves great attention ; 
there is nothing that the lover of plants feels the want 
of so much as good representations of the vegetation of 
other lands. Scarcely anything of the kind exists at 
present, artists generally represent the trees under a 
few conventional forms, seldom noting them with any 
accuracy in nature, and usually fill up the details of 
their finished dramngs by the aid of imperfect memory, 
or, still worse — imagination. Flowers and single plants 
we can see in our conservatories and stoves, but the un- 
traveUed botanist is at a loss when he tries to pictm-e to 
himself the glorious vegetation of tropical climates ; 
language may go far, but good dra"wings are the great 
desideratum in this depai-tment of physical geography. 
Passing to the " Annotations and Additions," we 
meet -with a very interesting note upon the probable 
numbers of existing plants. This is of considerable 
length, and we shall select only portions of it, giving 
the general results of the calculations at which the 
author arrives. 
" If, then, -we would attempt to solve the question spoken of in 
the early pai-t of this dissertation, hy giving in an approximate 
manner the numerical limit (le nombre limite of French mathe- 
maticians), -which the whole phanerogamce, now existing on the 
surface of the earth, cannot he supposed to fall short of, we may 
perhaps find our safest guide in a comparison of the numerical 
ratios (which, as we have seen, maybe assumed to exist between 
the different families of plants), -with the number of species con- 
tained in herbariums, and cultivated in our gi-eat botanic gar- 
dens. I have said that in 1820 the number of species contained 
in the herbariums of the Jardin des Plantes at Paris was ah-eady 
estimated at 56,000. I do not permit myself to conjecture the 
amount which the herbariums of England may contain ; but 
the great Paris herbarium, which was formed with much per- 
sonal sacrifice by Benjamin Delessei-t, and given by him for free 
and general use, was stated at his death to contain 86,000 species ; 
a number almost equal to that which, as late as 1835, was con- 
jecturiiUy assigned by Lindley as that of all the species existing 
on the whole earth. (Lindley, Introduction to Botany, 2d edit., 
p. 504). Few herbariums have been reckoned with care, after a 
complete and strict separation and withdrawal of all mere 
.^ 
