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Show PARTICULAR CONSIDERATIONS ON THE each other at the time.* It has likewise been ;_oted that the globules of the blood are reprodu~ed b) th~ .expansion of contained granules ; they ar.e, 1 n short, d'ISt~nct m·o·anisms m:ultiplied by the sante fisszl!arous generatzon. So 0 that all animated nature 1nay be sa1d to be base<;I on this mode of origin; the fundamental fonn ~f ?rganz.c b.e· ino- is a a-lobule, haV?:ng a new globuie fornnng u_nthz:t its~lf, by ~hich it is in time discharg~d, and wh1ch IS again followed by anothe~· and anot~.er, In endless snccession. It is of course obv1ous that~ If thes~ globules could be produced by any process from Inorg~niC ele~entsJ we should be entitled to say that the fact of a transit from ~ho inor1ranic into the organic had b"een witnessed in t~at Instan~ e; the possibility of the commenceme~t of an1matc.d creation by the ordinary laws of nat~re m1ght be considered as established. Now it was given out some years ago by a French physiolog~s~, that g_lobules could be prod ,uced 1;n albumen by etcctnczty. It, therefore, these globules be identical with the cells which are now h~ld to be reproductive, it tnight he .said that the productiOn of albumen by artificial mea11s Is the only step n1.th~ process wanting. This has not yet been C!ffcctc<J but I.t Is known to be oqJy a chemical process, the mode of which may ~e any day discover~d in the laboratory, an_d two comp~unos perfectly co-ordinate, urea and alanto1n, have actually been produced. . . . . In suc.h an invesflgatwn as the. pres.ent, It _Is not un~ worthy of notice, that the prod~ctwn. oi. shell Is 3: nll:tural oncration which can be precisely lmitated artJ~cmlly. SilCh an incrustation takes place on bo~h the OU~Slde ~nd inside of the wheel in a bleaching establishment, !n ~v luch cotton cloth is rinsed free of the lime employed In Its purification. From the dressing employed by th.e weaver, tbe cloth obtains the animal mattPr, gelatin_; thts and the lime fonn the c-onstituents of the Incrustation, exa?tly ~s in natural shell. In the wheel employed at Catnne, In Av1·shire, whe1e the phenomenon was first observed by tl{e eye of science, it l1~d require~ ten years t~ r.rod.uce a co:1ting the tenth o: an Inch In th1ckne~s. T_his mcl_~station has all the characters of shell, displaying a h1ohly polished surface, beautifully iridescent, and, when bro- • See Dr. Martin Barry or1 Fissiparous. Gcncr.ati_on = J,amcson's Journal, Oct., 1843. Appear~nces prcc1sely S1m1lar have beeo detected in the germs of the crus1.ac!a~ / .. ORIGIN OF THE ANIMATED TR.IBEs. 91 ken, a foliated texture. The examination of it has even thrown some light on the character and mode of forma .. tion of natural shell. "The plates into which the substance is divisible have been 1ormed in succession, and certain intervals of time have elapsed between their formation; in general, every two contiguous laminre are flPnarated by a thin iridescent film, varying from three to the fifty millionth part of an inch in thickness, and producing all the various colors of thin plates, which cm-resw pond to intermediate thicknesses : between some of tlw lamince no such film exists, probably in consequence of the interval of time between their formation being too short; and between others, the film has been formed of unequal thickness. There can be no doubt that these iridescent films are formed when the dash-wheel is at rest during the night, and that when no film exists between two laminre, an interval to<? short for its formation (arising, perhaps, from the stopping of the worl{ during the day) has elapsed during the drying or induration of one lamina and the deposition of another."* From this it has been deduced, by a patient investigation, that those colors of mother-of-pearl, which are incommunicable to wax, arise from iridescent films deposited between the laminre of its structure; and it is hence inferred that the anim.al, like the wheel, rests period£cally from its labors in .fm·ming the natural substance. These, it will be owned, are curious and not irrelevant facts; but it will be asked what actual experience says t·especting the origination of life. Are there, it will be said, any authentic instances of either plants or animals, of however humble and simple a kind, having come into existence otherwise than in the ordinary way of generation, since the time of which geology forms the record? It may be answered that the negative of this question could not he by any means formidable to the doctrine ot law-creation, seeing, that the conditions necessary for the operation of the supposed life-creating laws may not have existed within record to any great extent. On the other hand, as we see the phys1c~l laws of early times still acting with more or less force, jt might not be unreasonable to expect that we should still see some remnants, or partial and occasional workj ngs of the life-creating energy • Mr. Leonard Hornor and Sir David Brewster, on a ~ubstanoo resembling shell.-P!tilosopltical Transactions, 1836. |