532 
quired for flight; the corresponding ganglia 
contained within the thorax exhibit a size and 
development proportioned to that of the mus- 
cles they are destined to animate; and the 
winged Insect becomes thus competent to the 
exhibition of feats of strength and activity not 
bess paralleled in any other race of living 
ings. 
On taking a survey of the molluscous or of 
the vertebrate divisions of the animal creation, 
the same great law is every where apparent, 
and we are reminded, on all hands, that a strict 
rallelism exists between the condition of the 
Ocomotive system, whatever may be its cha- 
racter, and the perfection of the nervous appa- 
ratus, whereby muscular movements are con- 
trolled and directed. As a necessary conse- 
quence of the above intimate and inseparable 
relation, which invariably exists between the 
organs of motion and those of innervation ; 
and allowing, as modern Zoologists all admit, 
that the nervous system, whatever may be its 
condition, is to be regarded as the ruling pri- 
mary portion of the animal economy, we are 
naturally led, therefore, in reviewing the mus- 
cular system generally, to take this great phy- 
siological axiom as our guide, and beginning 
with the simplest forms of life to trace the first 
appearances and successive complication of 
the motor organs as we advance through the. 
different classes of animated beings. 
In the Cuvierian classification of the Régne 
Animal a!l the lower animals, originally con- 
founded under the general name of Zoophytes, 
are included in one great division, called 
Raprata, from the circumstance that many 
forms of these animals exhibit more or less of 
a radiated arrangement in the general outline 
of their bodies. For the term Raprata, in 
the article Anima Kincpom of this Cyclo- 
pedia, Dr. Grant has substituted that of 
“ Cyctoneura,” acknowledging, at the 
same time, that the name selected by him 
was of equally partial application, and conse- 
quently unsatisfactory; inasmuch as, in the 
great majority of the animals ranged under it, 
so far from any nerves being visible, “ disposed 
in a circular manner around the oral extremity 
of the body,” not a trace or vestige of nervous 
fibre is by any means discoverable; and, 
moreover, many of the animals thus grouped 
under one denomination are so remote and 
dissimilar from each other in every feature of 
their economy, that it is impossible to regard 
them even as being organized according to the 
same type. As regards the condition of their 
muscular system, the most striking differences 
are at once perceptible; the Sponges, the 
Polyps properly so called,* the Polygastrica, 
and the Acalepha, have the texture of their 
bodies so soft and gelatinous, that not a mus- 
* In the article referred to, polypiform animals, 
with ciliated tentacula around the mouth, ure 
classed with the Polypifera. Recent observations 
made by Lister, Milne Edwards, Ehrenberg, and 
Dr. pie Ke Farre, have, however, since shewn such 
creatures to be so far removed in their general 
organization from the true Polyps, that they now 
constitute a distinct class under the title of Bryozoa, 
MUSCULAR SYSTEM. 
cular fibre is by any means apparent in any of 
them ; while, = e oer. eae the chen ae 
derms have muscular systems constructed u pom 
exceedingly elaborate and complex principles. 
Taking the nervous system for our guide, itis 
at once evident that the presence of nervesand . 
of muscles goes hand in hand,andthe RapiaTA 
of Cuvier or the Cycroneura of Grant is at 
once separable into two great groups, one divi- 
sion being without either visible nerves or mus- 
cles, while the other is found to possess b a 
Classifying them, therefore, according to 
principle, and adding to the list o a 
animals some which, in the article ANtMaAt 
Kincpom, have, as we think, been erroneously — 
included in the Diploneurose (articulated) sub- — 
kingdom, they readily range themselves under 
the following denominations :— 7 
Acrita. ' 
Anima!s with neithcr nerves nor muscles. 
Agastrica. 
Polypiphera. 
Polygastrica. 
Acalephe. 
Sterelmintha. 
* 
‘af 
Nematongeura — Animals both 
of nerves and muscles, either without percep 
tible ganglionic centres of innervation, or wher 
these do exist, they are extremely radimentary, 
and not arranged in any parallel series. Thi 
division will include ae 
Celelmintha, | 
Bryozoa, a. 
Rotifera, * 
Epizoa, ‘i 
Echinodermata. ee 
The term Agastrica is here proposed te i 
clude those ad forms of peta existen 
which obviously form the transition from th 
Vegetable to the Animal Kingdom; many « 
them indeed seeming rather to belong to t 
former than to the latter division of the or 
nized world. Such are, for example, the coi 
fervoid animalcules, which, in their structu 
and mode of reproduction, are evidently nes 
allied to vegetables, although from the see 
ingly spontaneous movements of which si 
the Oscillatoriw, &e. are capable, they have! 
claimed by Zoologists as belonging to theit 
partment. The Sponges ( Porifera, Grant) 
equally allied to vegetables in the nature 
living parenchyma that invests and forms 
porous or reticulated skeletons; and mo: 
mately related to these,notwithstanding the 
rent texture of their framework, are many ¢ 
lithophytous Corallines and Fungia, th 
portions of their skeleton being in like n 
deposited in an organized soft tissue, the 
nature of which is by no meansas yet ¢ 
blished. All the above plant-like fe 
however, in one grand and striking 
stance,—they are devoid of any stom: 
digestive cavity, a feature of their 
which of itself would be sufficient 
doubt whether they are strictly entitled — 
regarded as animals or classed with the ¥ 
ble creation. ’ 
' 
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