1797.] Internal and External Struéture of the Clafs Vermese 
his having left Barcelona:—of this laft 
meafurement, however, we have as yet 
had no accounts. This great and me- 
morable operation will probably be com- 
pleted in the courfe of the enfuing year ; 
when the French republic will have im- 
mortalized the firft years of its eftablith- 
ment, by the adoption of a Metrical Sy{- 
tem, that fhall be the refult of recent 
difcoveries, or rather of confummate 
knowledge, acquired in the phyfical and — 
mathematical {ciences. 
remeber! e 
Analyfis of a Memoir, on toe internal and 
external Strudture of thofe Animals that 
are ufually arranged under the Clafs 
VERMES. « By S. Cuvier. Read at 
THE SOCIETY OF NATURAL His- 
TORY, at Paris. 21 Floreal 1796- 
Tue circulation of the blood, and the 
ergans of refpiration, form the bafis 
upon which Cuvier’s new claffification 
of Vermes is founded. All white-blood- 
ed animals, may thercfore be divided 
mto, * 
1. Thofe which have a heart anda 
complete vafcular fyftem, and refpire by 
branchie. 
2. Thofe that are deftitute of a heart, 
in whom the circulation is carried on by 
a fimple dorfal veffel, and who refpire by 
trachez. : 
3. Thofe that have neither hea, nor 
_veffels, nor refpiration. 
All animals with a heart, have like- 
wife branchiz ; thofe without that organ, 
have only trachée. The term re{piration 
by branchia, is applied where the fan- 
cuiferous veffels ramify very minutely on 
certain furfaces, that are expofed to the 
ambient element, whether air or water, 
there to receive certain modifications, 
neceflary to the nutritive fiuid. Refpi- 
ration by trachez, on the contrary, 1s, 
when the furrounding element, whether 
air or water, is abforbed by certain vef- 
fels, which ramify within the body of 
the animal, there to produce the necef- 
fary effeét on the blood ; it matters not 
whither thefe orifices are protruded from 
the body, forming tentacles of various 
fhapes, or are merely. pores in the inte- 
guments. . 
Now where the blood-veffels ramify fo 
minutely as in the branchiz, a heart is 
neceffary to force the blood through fuch 
flender tubes: where the heart 1s want- 
ing, the branchie mutt be ufelefs, and 
the blood not being able to reach the en- 
veloping medium, it is neceflary that 
209 
this fhould be conveyed to the blood by 
abforption. 
A fecond general law is, that where 
the heart and branchiew are found, the 
iver alfo exifts, and where they ceafe, 
this vifeus ceafes alfo; the cuttle-fith, 
fnails, and all the bivalves, have a liver, 
as well as the red-blooded animals. On 
this account, the molluica ought to be 
placed at the head of the white-blooded 
animals, immediately after the fithes, and 
before the cruftacea and infeéts. 
The fubdivifions of this fyftem, are 
formed by the ftruéture of the central 
organs of fenfations, that is, the brain 
and {piral marrow. Here, again, we meet 
with three grand diftinétions. 
1. The medullary fubftance is col- 
leéted into a few lobes, fituated clofe to 
each other, forming a circle, whence the 
nerves iflue in all directions : 
2. The lobes of medullary fubftance 
are difpofed along the whole length of 
the belly, forming ganglions, from each 
of which, the nerves fhoot out in tranf{- 
verfe directions; the ganglions are con- 
nected to each other, by a very flender 
medullary cord, that pafles the whole 
length of the animal. 
3. Lhe diftinétion of brain and nerves 
is entirely wanting, and the medullary 
pulp is {pread through the whole fup- 
ftance of the body. 
With regard to the organs of refpira- 
tion, it is evident, that the animals of 
the firft divifion are the moft perfect, 
and thofe of the third the leaft fo; this 
alfo is the cafe with the organs of fen- 
fation. Jn man, the contents of the fcull 
are coljleéted into a globe; in quadru- 
peds and birds, this globe is elongated; — 
in fifh, the brain begins to feparate ; in 
the cuttle-fifh, it 1s divided into four 
diftinét detached lobes ; in infects, thefe 
lobes are diftributed through the whole 
length of the body; in_polypes, the dif- 
fufion takes place toa {till greater ex- 
tent, there is no common centre or {en- 
forium, and, therefore, each part 1s capa- 
ble of forming a feparate animal. 
From the above-mentioned differences 
of ftruéture, in the organs of refpira- 
tion and fenfation, are formed the fol- 
lowing fix orders, with their effential 
characters : ; 
1. Mellufce. AM animals of this clafs, 
have a mufcular heart, furnifhed with 
valves, acomplete fyftem of fanguifer- 
ous veffels and branchiz for refpiration ; 
they have a brain and nerves, and moft 
of them external organs of fenfation, as 
eyes 
= 



