332 
ON THE DEVELOPMENT OF CERTAIN PLANTS. 
tural production, but a manufactured article: 
that Ceylon gamboge, if freed from incidental 
fibrous matter, corresponds almost exactly 
with Siam gamboge : that, therefore, they 
are probably produced by the same plant : 
that Ceylon gamboge possesses precisely the 
same medicinal properties ; and that this 
variety, if more carefully colleeted, may, in 
all probability, be applied with equal advan- 
tage to every economical purpose which is at 
present served by the finest pipe gamboge of 
Siam . — Repertory of Arts, May, 1836. 
A. T. 
PRINCIPLES OF CLASSIFICATION 
IN THE ANIMAL KINGDOM. 
By Professor Agassiz. 
Although the principal groups of animal 
are impressed with such characters as to be 
easily recognised and to admit of little doubt, 
yet their order and succession have been 
determined by no general principle. This 
appears from the discrepancy in the position 
assigned to them by the most eminent systema- 
tists, each of whom has assumed, arbitrarily, 
some organ or system of organs for the basis 
of his arrangement. Piofessor Agassiz, (at 
the last meeting of the British Association), 
after adverting to some German naturalists 
who alone have sought after a general princi- 
ple which should be satisfactory to “ philoso- 
phic naturalists,” passed in review the clashes 
of the animal kingdom, each of which, he sta- 
ted, exhibited in an eminent degree the deve- 
lopment of some one of the animal functions. 
"While vertebrate animals (with man their 
type) arrive at the greatest perfection in the 
organs of the senses, the invertebrate offer 
in the class of worms the representative of 
the system of nutrition, in Crustacea of cir- 
culation, in insects of respiration, and in mol- 
lusca oi generation. The Professor next pro- 
ceeded to demonstrate in what manner each 
subclass of vertebrate animal derives its pe- 
culiar character from some one element of 
the animal economy. 
This predominant element is the bony skele- 
ton in fishes, the muscular structure in reptiles, 
the sensibility of the nervous system in lurds, 
and the perfection of the senses in mammalia, 
which therefore reproduced the distinguish- 
ing character and constitute the type of verte- 
brate animals. He next showed tliat each of 
the other subclasses of the higher group is 
represented among the mammalia along with 
its own peculiar type. He explained his rea- 
son for the fourfold division which he had 
adopted in the subclass, pointing out the close 
affinity which connects the ruminantia, the 
pachydermata, the rodentia, the edentata, and 
the herbivorous marsupialia, (ia none of w'hich 
is the true canine tooth developed,^ which he 
considers as forming a single group ; in ano- 
ther he unites those characterized by the pre- 
sence of the canine tooth in its proper func- 
tion, (as an instrument of nutrition, not mere- 
ly of defence,) viz. the carnivora and those 
marsupialia which partake of their character, 
and the quadrumana. The cetacea form a 
group in themselves; and man another. The 
manner inwhich these represent the subclass- 
es of vertebrata was exhibited by the compari- 
son of 
Cetacea, with Fishes, 
Ruminantia , See. Reptiles, 
Carnivora, S^c. Birds; 
while man is the perfection and type of the 
mamrniferous conformation. 
Professor Agassiz then applied this prin- 
ciple to illustrate the order and succession 
of the groups in mammalia, by a reference 
to the order in which the fossilized remains 
of the vertebrata occur in the stratified 
deposits: 1. fishes, 2. reptiles, 3. birds, 4. 
mammalia. From the same consideration 
results the following arrangement of the repre- 
sentative groups among these last ; 1. cetacea, 
2. ruminantia, &c., 3. carnivora, 4. man, who 
thus in a twofold aspect becomes the culmi- 
nant point of the animal creation. 
ISINGLASS. 
From the experiments made by Mr. Smith 
in the United States, it appears that theintes- 
tines of the fish the gadus merluccius furnish 
the purest species of isinglass, (Journ. de 
Pharm.) not inferior to that obtained from the 
sturgeon. The swimming bladder of this fish 
is laiger than that of other species of the same 
family. It is cut out and washed with pure 
water, and then dried in the sun. "When par- 
tially dry it is pressed between wooden rollers 
as thin as paper. The long stripes of isinglass 
which are met with in commerce, are the 
intestines of the gadus morrhua.f 
SPONTANEOUS PLANTS. 
Few things are more extraordinary than 
the unusual appearance and development of 
certain plants in certain circumstances. Thus, 
after the great fire of London in 1666, the en- 
tire surface ol the destroyed city was covered 
with such a vast profusion of a species of a 
cruciferous plant, the Sisymbrium irio of Lin- 
naeus, that it was calculated that the whole of 
the rest of Europe co\rld not contain so many 
plants of it. It is also known that if a spring 
of salt water makes its appearance in a spot, 
even a great distance from the sea, the neigh- 
bourhood is soon covered with plants peculiar 
to a maritime locality, which plants, previous 
to this occurrence, were entire strangers to the 
country. Again, when a lake liappeus to dry 
u !», the surface is immediately usurped by a 
vegetation which is entirely peculiar, and quite 
different from that which flourished on its for- 
mer banks. When certain marshes of Zealand 
were drained, the Carex cyperoides was observ- 
ed in abundance, and it is known this is not 
at all a Danish plant, but peculiar to the 
north of Germany. — In a work upon the useful 
Mosses by M. de Brebisson, which has been i 
announced for some time, this botanist states | 
that a pond in the neighbourhood of Falain 
* Philosophical Magazine No. 43. 
•1 Thomson’s Records, No. 3. 
