20 
GENERAL REVIEW 
primary organ of the body; and as this delicate system of nerrous matter requires for 
its protection a bony column of vertebra?, it is necessary to assume the existence or 
absence of a vertebrated column as the foundation of our primary divisions of the 
Animal Kingdom. 
We shall defer the greater part of our observations upon systems in general, until 
we come to treat of the history of Zoolcgy. At present our remarks will be confined 
to the theory of one universal chain of existence, which may not improperly be termed 
the theory of the straight line; and we believe it to have as little foundation in Nature 
as the corresponding theories of the circle. 
On contemplating the long chain of organized beings, we observe them to be- 
come complicated by degrees, without sudden brcalcs and transition?. The lowest 
have nothing hut a simple root ; — the highest possess an exceedingly complicated 
brain. In passing from one cxtrem.c to the other, we first find imperfect plants, or 
wo should rather say, plants of ver)" simple structure ; some of which are composed 
of an umbrella-shaped covering attached to a root, — that essential organ of every 
plant, excepting perhaps the Krubut; others apparently consist but of simple leaves ; 
and some have only pcdiculatcd flowers without leaves. On the other hand, we find 
plants composed at once of a root, leaves, stem, and flowers ; while the flowers cither 
simply present only an ovarium, stamens, and pistils — organs essential to the produc- 
tion of seed — or, besides these indispensable organs, they also exhibit pcLils and a calyx, 
more or less complicated. 
Ill the Animal Kingdom, the successive gradations in the complication of structure 
are much more numerous. To the stomach, which wo have already mentioned as 
composing the most simple of animals, we see added, in succession, various appendages, 
moveable tontacula, and afterwards some rudimentary appearances of vessels filled with 
white blood. Continuing our observations further, we begin to perceive some scat- 
tered nervous filaments, and then some colourless muscular fibres. Soon after, wo 
find that the digestive canal becomes more complicated; instead of onoorificc, wc now 
find two ; at length we arrive at an elongated ami convoluted intestine. In yet 
higher gradations than these, we perceive lungs, tracheai, and gills, with complicated 
muscles, destined to move particular members, connected by joints of an elaborate 
mechanism. Further upwards, wc perceive hearts of a simple construction, evident 
oi’gans of sensation, distinct arrangements already of a complicated character, for 
continuing the species, ganglions or knots of nerves, with a maiTOw dilated at one ex- 
tremity. Finally, we arrive at a vertebrated column, perfect senses, a spinal marrow 
enclosed in a bony tube, a skull, and, to crown the whole, a beautifully-organized 
brain. 
However perfect this chain of animated existence may at first sight appear, wc must 
admit that many objections may be made to its details. The transitions are often 
harsh, and by no means always very obvious, from one link to another ; and if it be 
true that, whatever fractures a link, 
“ Tenth or ten-thousandth breaks the chain alike,” 
wo fear that the advocates for one uninterrupted chain of existence, from the minutest 
conferva or lichen, to the throne of the Eternal, will find many chasms which cannot 
bo united even in the most fertile imagination. 
In attempting to trace this supposed chain betweenthe lowest animals and the Ver- 
tebi-ata, we find that the progressive development of the organs of nutrition and of 
sensation greatly disturb its uniformity. The organs of sensation and motion have 
already arrived at a great degree of perfection in animals, in which we can find no 
heart, no evident circulation, or observable respiration. On the contrary, in other 
beings, an opposite result may be observed ; and while some have a heart already mani- 
fest, with vessels and complicated respiratory organs, we find that the organs of sen- 
sation have but a very slight degree of development. 
If we bo desirous of forming in the imagination one of these universal chains of 
existence, wc have but to assign to the mountain rocks, or to the filaments of the as- 
bestos, the faculty of absorbing nourishment and of growing, and we have formed the 
idea of a being rescmbUug a plant, which possesses two orders of functions, — the one 
essential to the preservation of the individual, and the other necessary for the conti- 
nuation of the species. To these two subordinate, yet well-defined functions, let us 
add the powers of voluntary motion and sensation, — let us add a central cavity for di- 
gesting the aliment; and wc thus produce an animal of the lowest possible degree. To 
this moving, sensitive, and instinctavc mass, let us join numerous nerves traversing 
every part, senses of a complex form circumscribed in special organs, a central brain, 
the iiLStrument of perception and volition ; let us add to these, muscles for obeying the 
determinations of the Will, with, a skeleton for affording a support to the muscles, and 
firmness to the whole fabric, and an animal is constructed of the highest order and of 
the most complicated form. On the summit of this series of superior beings, let us 
place Man — a being remarkable for the vertical situation of his body, tho volume of 
his brain, the perfect adjustment of his senses ; for his Prudence, Curiosity, and Wis- 
tlom ; for the energy of his Will, the lights of his Reason, and the sublimity of liis 
Genius- 
hlanv philosophers, but especially Bonati and Charles Bonnet, have ingeniously at- 
tempted to arrange all the bodies in nature, in a manner similar to what we have here 
attempted to explain, according to the progressive analogies which they offer to the 
observer. They have endeavoured to pass by insensible gradations from one natural 
production to another, just as in the rainbow or solar spectrum we arrive, by unjier- 
ccived transitions, from colour to colour, from the violet ray to the blue, from tho 
blue to the indigo, from this to the green, yellow, orange, and red, and finally, from 
the red, by a new circle, round again to the violet. The philosophers whom wo have 
just named thought that every thing in nature formed one long chain, without break 
or interruption, and Bonnet illustrated his views in the following manner:— 
lie thought that tho talcs, the slates, the schists, but especially the amj-anthus, 
formed a natural and easy transition from the Mineral to the \ cgctablc Kingdom. 
Again, tho Sensitive Plant, as well as many species of Algm am! Fuci, formed a 
natural link between plants and the most simple kinds of animals. After that, 
a thousand different shades and nice transitions presented themselves in the Ani- 
lual Kingdom. If certain sppi*i<*s of simnlo P.lvpi form tlic connecting link be- 
OF LIVING BEINGS. 
tween the two great Kingdoms of organized Nature, they servo, at the same time, 
to unite the Infusoria, those microscopic inhabitants of fluids, with tho Acaleplise, 
Sea-nettles, or IMeduss. Agdin, these last-mentioned animals conduct us gradiu 
ally to the Worms and Mollusca, on the one hand, and, for different reasons, to tho 
Insects, Uie Araehiiides or Sjuders, and the Crustacea, on the other. Procee<ling 
further, we are led from the aquatic Worms to tho Mollusca, by means of the Hiru- 
dincffi or Leeches, and from the Mollusca to the Reptiles, by the Limax or Snail. 
The Reptiles, in their turn, form tho bond of connexion with the Fishes, hy means of 
the tadpoles, the young of the Frog, in the same manner as the Insects, by another 
circle, merge successively into tho Worms, Mollusca, and Reptile?, by their Larv» 
and Caterpillars. Water-serpents arc not very different from E 'is. The Fishes 
are related to the Birds by means of the Flying I’Ish, the Trigla or Gurnard, and the 
Exocetus ; and, finally, the Birds are linked to the Mammalia by the Ornithorynehus 
in one sense, .nud by the Bats and Hying Squirrels in another. 
ISIany analogies of a similar kind arc traced by the ingenious Bonnet. Thus, the 
Palmipedes, or Wcb.Footed Birds, are said to lead us, by a gentle transition, to the 
Fishes, just as the Penguins and Ostriches merge gradually into tho Mammalia. Wc 
are conducted from the Mammalia to the Fishes by tho Otters and Wlialcs, to the 
Reptiles by the Seals, and to the Birds by the Bata and the spiny Echidna?. The 
transition is not abrupt, according to Bonnet, from the Monkey to Man, and Man 
himself is formed after tho image of his Creator. He add?, with his usual elegance, 
“ Un seiil etre est place hors do la chaine, ct e’est celui qui I’a creee.” (One being 
alone is placed without tho chain, and that is — Tiix Creatou.) 
We should not have dwelt thus at length upon tlicso analogies, many of which are 
altogether imaginary, were we not fully persuaded that even these imperfect compari- 
sons are useful in giving a genend idea of living beings to persons ignorant altogether 
of Zoology, and consequently are appropriate for these Introductory pages. 
But if Naturalists have failed in attempting to resolve tho intricate dispositions of 
Nature by the strmght line, they arc equally at fault in proposing Circular thcorio's. 
In vain do they attempt tho solution of problems, which even tho highest geometry 
cannot resolve, by the simple theories of tho straight line, and circle. Seduced by 
an excessive love of simplicity, they depart from those physiological riews whicli should 
form the basis of a sound system of classification. 
Mr ^V. S. Macleay was the first proposer of the circular system. ' He thought that 
the several kingdoms of Nature, as wc*ll as their various subdivisions, returned into 
themselves, and may therefore be represented by circles. He considered tlic number 
Five as tho basis of this system. Each circle formed precisely five groups ; each of 
those composed other five, and so on, until we arrived at the extreme limit of tlie sys- 
tem. The proximate circles were thought to bg connected by the intervention of lesser 
groups, to which the term osculant was assigned; and relations of analogy wcie 
pointed out between certain corresponding points in the circumferences of contiguous 
circles. We must admit that this theory has been applied with some degree of success 
to two of the branches of Natural History — Ornithology and Entomology; and the 
reason of this evidently arises from tho great number of objt'cts included in thes* 
branches, which gives an unusual facility to the circular theorist. 
The objects of Natural History are iufinito in number; that is to say, their number 
is so vast that no individual, however industrious, can possibly, within the usual period 
of a lifetime, comprehend their various phenomena and relations. Again, these phe- 
nomena themselves ai‘e inuumcrablo; the connexion of their properties is absolutely 
overwhelming, by their intricacy and tlic closeness of their approximation. If, then, 
wc are willing to form a Circular theory, the basis of which is intended to be three, 
five, seven, or any other number, arbitrarily assumed, wc have but to take some one 
leading group ; and, casting about for some other leading group which can join on to 
this first one, and a third on to the second, wo must necessarily fall in with some 
other leading group which will join on to the first, and thus a circle will bo formed. 
We have said necessarily, because, according to the common theory of probabilities, 
the number of objects being infinite, and the number of groups, and tho relations of 
groups, also infinite, we must necessarily, without the aid of any very fertile imagina- 
tion, fall in with some leading property which will conduct us to the spot whence we 
started. 
This ca^Kibility of arrangement in circles is not exclusively a law of Nature, as tho 
advocates of the circular theories would lead us to suppose. Works of Art may be 
arranged in a similar manner. The merchant may arrange his goods, or the librarian 
his books, in circles, according to the most approved principles. Commencing with 
folios bound in morocco, and passing through all the gradations of binding, size, and 
colour, ho might be easily conducted, by these and other relations, to the unbound 
folio, stitched in red cloth, which would lead him, by a nice transition, back again to 
his original starting place; and if any difficulty attached to this arrangement, it niigh^ 
easily be remedied by the invention of groups normal or aberrant. 
Wc are apt to imagine, on falling in by accident with any of the recent works pro* 
posir^ Circular theories, that wc have mistaken treatises on Geometry or Mechanics 
for volumes of Natural History. Considering internal organization and laws of co- 
existence, as subjects irrelevant to Natural History, they substitute (what a distin- 
guished circular theorist of the present day rightly terms) the “ wheels within wheel*” 
of a fertile imagination. They may not be unaptly compared to the Ptolemaic system 
of Astronomy ; and like it, could only be tolerated in the infancy of science. 
** With cycle on epicycle, — orb on orb,” 
they almost call from us the just, though somewhat startling, observation of Alphonso 
X. king of Castile. 
The combinations of properties among natural objects are so numerous, that many 
beings must necessarily have tho same part?, and there must always he a great uunibcf 
presenting vor}^ slight differences. On comparing those resembling each other, it ** 
easy to form series, which will appear to descend gradually from a primitive type* 
These considerations have accordingly given rbc to the formation of a Scale of Being» 
and to Circular Theories; tho object of the former being to exhibit the whole in on® 
series, commencing with the most complicated, and ending with the most simple or- 
ganization, — and that of the latter to form two series, wliich, like two semi-circIo5, 
