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demonstrated. In some groups, they pletely puzzled them. Vicq. d'Azyr, elude our research, perhaps from their M. Datrochet and others proposed an extreme delicacy ; in other groups, as ingenious solution of the difficulty ; they the rotifera, the minuteness of the considered each wheel to be composed animals themselves renders the detec- of an exceedingly flexible structure, and tion of such organs almost hopeless. that, while in reality stationary, it beAnd, although Ehrenberg considers that came thrown into a series of unduhe has succeeded in discovering, not | lations, or alternate elevations and deonly nervous filaments, but even nervous pressions by the action of muscular ganglia, there is perhaps reason to sus fibres ; the elevated portion sinking, pect that he may have been misled by the sunk portion being raised, and so on appearances. We do not mean to say in succession with great rapidity round that nerves do not exist in these ani- the ring, as wave follows wave: the malcules, for many things render it rapidity of this alternation of elevation most probable ; but merely that it yet and depression, which would certainly remains to be demonstrated that the produce the appearance of a ruffled filaments described by him are such. stream running along and returning We shall again advert to this subject. into itself, may, as they suppose, so
The great division, called Nemato- deceive the eye as to give the appearneura, includes several classes, as bry- ance of a revolving wheel. It is, in
or polypes, with ciliated arms, deed, true, that the rotation of these external parasitic animals, termed Epi- wheels, is an optical delusion ; but, bezoa ; cælelmintha, or certain intestinal yond this, it is now proved that there worms; star fishes and echini ; and the are really no wheels at all, and that subjects of our present observations, the the appearance of these is produced by rotifera.
circlets of minute cilia or fibrils, while The rotifera, or wheel-bearing ani- the apparently rotatory motion in quesmalcules, are so termed, from the ap- tion is produced by a series of progrespearance of certain wheels often seen sive undulations in consequence of the rapidly rotating, in various situations alternate and orderly extension and conon the anterior part of the body near traction of each separate fibril. the mouth.
because According to the observations of Dr. they were so regarded by the earlier A. Farre, (Phil. Trans. 1837,) the cilia, microscopic observers, who seeing them under a microscope of high powers, rotate, as it appeared, with great ve. present an appearance of waves rolling locity, were completely at a loss how round and round in a circle ; each wave to account for their presence and mo is produced by a number of cilia, those tion, or to conceive of the nature of their forming the highest point being at full organic union with the body of the stretch; the others, folded down upon animal itself. It scarcely need be said themselves, in an increasing ratio to that the continued revolution of any the middle of the interval between two part or appendage of the body, round waves, where they are most completely an axis, (as a wheel turns on its axle,) lowered: these, however, become in is quite inconsistent with the possibility turn the most elevated, and those which of an organic union of such an appen were the highest, the most lowered, dage to the body : this, indeed, was and so on in alternate succession, and with felt by the earlier observers, yet they great rapidity, the waves appearing to saw the wheels of these animalcules roll onwards. The annexed diagram, whirling round and round, and were allowance being made for its rudeness, unable to solve the enigma which com
will serve to explain the process.
These cilia are certainly endowed with, by means of muscular fibres cc, the voluntary motion ; they are regulated
Fig. A. in their actions by the will of the animal; they can be urged into movements of extreme rapidity, or put into gentle and tranquil action, or stopped in an instant. Sometimes, a portion only of the circlet of cilia is in action, while the other portion is quiescent, and sometimes a few cilia alone, are seen slowly bending and then stretching themselves ; when all at once, the whole begin to work with the utmost energy, wave succeeding wave, with wonderful velocity. It is by the action of these cilia, that the animalcule rows itself through the water, and traverses the tiny ocean in which it revels, full of animation. They are not, however, exclusively organs of locomotion; they serve for the acquisition of food : fixing itself, by means of a pair of forceps, terminating the body, to some stationary object, (as, for example, an aquatic plant,) the animalcule sets its cilia in action, and thereby produces a whirlpool in the contiguous water, converging to the creature's mouth, and hurrying thither such minute particles, either
7 of an animal or vegetable nature, as are drawn into the mimic charybdis. cilia themselves being drawn into It appears that the cilia of these animal sheath, in the animal's body. cules, whatever their own structure may be, are governed by a muscular apparatus, which is very conspicuous, and which retracts them, when not in use, within a kind of sheath, where they are safely lodged, till their action is required.
Having thus explained the real character of the supposed wheels, whence this group of animalcules has received its general title, we may proceed to more particular details.
The rotifera may be described as shell-covered animalcules, their body being inclosed in a moderately firm or horny investment, but of extreme delicacy, and very transparent, so that the internal viscera may be perceived through it. The upper, or free margin of this shell, is often indented, or ornamented with regular projections, and is continued by means of a fine membrane to the bases of certain elevations around the mouth, termed lobes, rom which arise the
cilia already described. See Fig. A. This membranous continuation of the shell does not confine the ciliary apparatus, but permits it to The rotifera present great variations be retracted at pleasure within the shell, I of form and colour ; but all have at
the posterior extremity of the body a tinctly seen, under a powerful micropair of forceps or pincers, instruments scope, which also demonstrates their of prehension, by which they attach effects upon the bodies of the smaller themselves at will, to stationary objects : animalcules on which the various species in some, as in Brachionus urceolaris, prey; for, as with fishes, they are the these pincers terminate a long mus food of each other, and the warfare is cular tail-like appendage ; but, in others, perpetually carried on. The hardness as for example, Notommata clavulata, of these teeth, is not a little surprising ; the pincers terminate a mere projec- they may be detached from the body tion.
of the animalcule in a perfect condition, It has been already observed, that it and be submitted by themselves, to is by the whirlpool which the action examination beneath a microscope; they of the cilia produces, that aliment is vary in minor particulars, as form and brought to the mouth of these roti- size, in every species ; but their essenferous animalcules. The mouth or oral tial characters appear to be the same aperture leads into a gullet, which va- in all. ries remarkably in size in different From this teeth-furnished gizzard, species : in some, it is very capacious; or preparatory receptacle, a passage, but in others, as in Brachionus urceo- varying in length in different animallaris, (fig. B) it is a narrow canal. cules, leads to the true stomach or diThe gullet leads to a gizzard, or pre- gesting cavity, to which the food, after paratory receptacle, (e), in which, by being subdivided, is conveyed. See means of a curious apparatus, the food F. in fig. A. and B. The form and the is either ground to pulp or cut in frag- relative capacity of the stomach, like ments. This apparatus is described by those of the gizzard, are very variable; Ehrenberg as consisting of three teeth, but in all these rotiferous animalcules which, by the action of the gizzard and this viscus is furnished with certain of certain muscles belonging to them, appendages, which are regarded as bework vigorously on each other, and so ing of a glandular structure, and desmince to pieces whatever is subjected tined to secrete a fluid essential to the to their operation. These teeth are three performance of digestion. Ehrenberg in number, as in this sketch, and con- considers them as analogous to the
pancreas of the higher orders of animals, but without sufficient grounds. Professor Jones, on the contrary, believes them to be the first rudiments of a liver, or biliary apparatus, and we think this opinion much more entitled to assent than that of Ehrenberg : every analogy indeed favours it; and we know the liver to be “ the most important
and the most universal of the glandular sist of one central and two lateral or organs subservient to digestion.” We superior ones : the central tooth is ap- find an appendix supposed to represent parently fixed, and has two flattened the liver in insects; and in the molfacets on its upper surface, one for each lusca and crustacea this organ is exsuperior tooth to work upon. Each of tensive, but of a rudimentary structure. these superior teeth consists of two por- In Brachionus urceolaris, (fig. B. 99,) tions, namely, a basal portion, fixed to this presumed biliary apparatus consists the walls of the gizzard, and serving of two processes united to the upper for the attachment of muscular fibres, portion of the stomach; but in Notomand a free moveable portion which may mata clavulata, (fig. A. 999,) three be regarded as the real tooth, while elongated sacculi are attached to each the other serves as a jaw. These free side of the stomach, and of these the portions work with their inner edge uppermost on each side is the largest. upon the facets of the central piece, Great, however, is the variation of these and this edge appears to be jagged or appendages as it respects form, number, serrated, the better to tear the sub- and magnitude, in the rotifera ; but stances on which it acts. Minute as are they appear to be always present. these curious organs, the transparency We have already intimated that bands of the rotifera, permits them to be dis- of muscular fibres have been distinctly
seen in these rotiferous animalcules: organization. But it is not only a some run longitudinally from the lobes nervous system which Ehrenberg beon which the cilia are situated, and are lieves that he has discovered in the roinserted into the membrane lining the tifera, he also considers that he has shelly covering of the body; these may demonstrated a vascular system, or an be termed the retractor. muscles of the arrangement of vessels, for the circucilia; but, besides these, others running lation of the nutritive fluids of the transversely have been detected. The animal structure, and he states that use of these latter bands of muscular these vessels have a transverse course, fibres is not clearly ascertained; but it running across the body ; but it is difis supposed that, by their contraction, ficult to imagine how he could distinthey may act upon the shell to the guish between them and muscular lining membrane of which they are fibres, running in the same direction ; affixed, so as to make the shell com and indeed the probability is, that the press the fluid which fills the body of vessels, as he conjectures them to be, these animalcules, and in which the are in reality muscular fibres, and not viscera float,) and force out thereby veins or arteries. the retracted ciliary apparatus by avert The existence of a true vascular sysing the membrane connecting them to tem, supposes an according developethe shell, which when the apparatus ment of the apparatus of respiration, is withdrawn, becomes inverted like the and Ehrenberg regards a minute horny finger of a glove, or the horn of a com- tube, found projecting in many species mon snail. These muscular fibres, both from the neck (fig. B. h) as serving for longitudinal and transverse, may be the admission of the surrounding water seen in fig. A.
into the general cavity of the body, But, besides the bundles of muscular and also for affording it exit; and he fibres thus presented, Ehrenberg states thinks that the alternate contractions that he has been able to detect nervous and dilatations of the body observable filaments and even minute ganglia, or in the rotifera effect this aquatic res, nervous centres, distributed in various piration, the water being drawn in by parts of the body, but with a certain the dilatations and expelled by the condegree of regularity. The existence of tractions ; and he states that when the distinct nerves and ganglia, supposing internal cavity is filled, the viscera are Ehrenberg to be correct, inasmuch as separated from each other so as to prethese organs would necessarily tend to sent clear and definite outlines, but that elevate the creatures in the scale of when the water is expelled, they approxanimal life, leads us to receive with less imate each other, and appear as a general astonishment a farther statement, given indefinite mass. The water being thus adby this philosopher, namely, that the mitted into the body of the animal, its deanimals in question are not destitute composition, and the aëration of the cirof some of the external organs of the culating fluid, is effected by certain little senses, and he believes that certain red vibrating points, or organs, attached to or coloured specks, which he has ob- two undulating viscera, running down served above the region of the gizzard, each side of the body; these little orare eyes; but he thus judges merely gans he describes as attached by a because these specks appear to be in footstalk to the viscera in question, and variably connected with the nervous to have their free extremity inflated, system. After all, it must be con- and perpetually vibrating. His first fessed that Ehrenberg's account both idea was, that they belonged to the of the distinct nerves and ganglia, and vascular system itself, but subsequently of the eyes, in these animals is to be he considered them as branchiæ, or received with caution. That nerves exist, internal gills, over which a mesh of is indeed not improbable ; but it does exquisitely delicate vessels ramify. It not follow that they have been detected. is easy to perceive that there is more In conducting microscopical experiments, of theory, and conjecture, than of aband especially with instruments of high solute demonstration in all this. But powers, appearances are apt to mislead ; theory has its uses ; it leads to farther and we are not aware that other natur- inquiry, and prompts the endeavour alists have established by their own either to confirm or confute it. observations those of Ehrenberg, as far. The rotifera are oviparous ; they proas relates to these important parts of duce eggs, from which the young are
excluded, sometimes while yet within, and attentively as the mighty and the the body of the parent.
massive. We are high and low, great The eggs of some of these animals and small, as to each other, but not to cules, appearing like minute transparent Him.” globules, are calculated to be, when It is plain and clear, then, that as first deposited, only the twelve thou- respects any criterion of complication sandth part of an inch in diameter; or refinement of structure, mere size, but they increase in magnitude, and of all the circumstances attendant on then constitute most interesting objects organized beings, is of the least imof microscopic examination. In an egg portance. of about the one thousand and seven Things animate or inanimate, are hundredth part of an inch in diameter, great or small only in our minds, only the included animalcule may be dis- as tested by the operation of our litinctly perceived, even the actions of mited and imperfect senses; but with the cilia may be distinguished, pro- reference to the operations of creative ducing the wheel-like rotatory appear- power, and in His sight, from whose ance previously described.
all pervading scrutiny nothing is hidAt certain times, the eggs may be den, the distinctions of great and small easily recognized before being deposited vanish. With Him who is omnipotent, by the animalcule, lodged in a long omnipresent, and eternal, number, magfloating sac, in the cavity of the body, nitude, and time are as nothing; these (fig. A. kk ;) for the transparency of the are terms which have relationship only creature is such as to permit the mi- to ourselves. To frame the smallest nutest parts of its internal structure to animalcule with an organization more be seen; but it often happens that the refined, more complicate than that of sac is empty. With respect to the the hugest whale, requires but the fiat frequency with which the eggs are of God; and he counts the myriads beproduced, nothing appears to be posi- yond myriads, with which the waters tively ascertained.
of this globe are tenanted, though our Such, then, is the general outline of minds recoil from the reckoning of the what we know of the structure of the numbers which revel in a little space. rotifera. They are active and vivac
Thus does nature, in the animalcules, creatures, and by the celerity and ad- which can be contemplated by us only dress of their movements, give delight through a powerful microscope, show to those who observe them. To see a forth the praise of God, and call upon shoal of them in a drop of water, avoid us to adore his power, his wisdom, and ing each other, in their mazy courses, his goodness.
M. and performing a thousand mingled evolutions, is perhaps one of the most interesting spectacles which the reflective can contemplate ; but this delight
SCRIPTURE.-No. VII. gives way to astonishment, or rather Let us now contemplate David, yet to meditation, when he perceives that upon his death bed, giving in charge the these creatures are elaborately con execution of his last
wishes to Solomon structed ; that they are organized with his son. Probably in consideration of an express relationship to their destined his youth, his inexperience, and the mode of life ; and that they enjoy their difficulties of his position, David thought existence like the fishes of the sea, or it well to put him in possession of the the birds of the air, or the wild beasts characters of some of those with whom of the desert.
he would have to deal; of those whom “ It is delightful,” says Sharon Tur- he had found faithful or faithless to himner, " to see by these miniature ex- self; that, on the one hand, his own istences, small almost to invisibility, promises of favour might not be forand by their careful organization, as feited, nor, on the other, the confidence finely contrived as that of the grandest of the young monarch be misplaced. creature, that greatness and littleness Now it is remarkable, that in this remake no difference to Him in his crea view of his friends and foes, David tion, or in his providence; they reveal altogether overlooks Mephibosheth, the to us that magnitude is nothing in his son of Jonathan. Joab he remembers, sight, that he is pleased to frame and and all that he had done; Shimei regard the small and weak, as benignly he speaks of at some length, and puts
UNDESIGNED COINCIDENCES OF