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Show 452 RUDIMENTARY ORGANS. CHAP, XUI. supported on the style; but in some Compositm, the rna l e fl oret s, wh I.c h of course cannot be fecu.n{' dat.e d,. have a pistil, which is in a rudimentary state, 1?r It IS not crowne d w1' th a st1'gma ,· but the style re. mains well de-veloped, and is clothed with hairs as 1n other compo-sitm, for the purpose of brushing the pollen out of the surrounding anthers. Again, an organ may become rudimentary for its proper purpose, a~d be used for a distinct object: in certain fish the s';lm-bla~d.er seems to be rudimentary for its proper function of giving buoy-ncy but has become converted into a nascent breathing ~rga~ or lung. Other similar i~sta:n~es could be given. Rudimentary organs in the Individuals of the same species are very liable to vary in degre~ of developm~nt and in other respects. Moreover, In closely allied species, the degree to which t~e same_ organ has been rendered rudimentary occasionally differs much. This latter fact is well exemplified in the state of the wings of the female moths in certain groups. Rud~mentary organs may be utterly aborted; and tlus implies, that we find in an animal or plant no trace of an organ, which analogy would l~ad us to exp~ct .t~ find, and which is occasionally found 1n monstrous I~dtv~duals of the species. Thus in the snapdragon (antirrhinum) we generally do not find a rudiment of a £fth ~tamen; but this may sometimes be seen. In tramng the homologies of the same part in different members ~fa class, nothing is more common, or mo;e ~e.cessary, than the use and discovery of rudiments. rhis IS well shown in the drawings given by Owen of the bones of the leg of the horse ox, and rhinoceros. It is an i~portant fact that rudimentary organ~, such as teeth in the upper jaws of whales and rumma~ts, can often be detected in the embryo, but afte~waidsl wholly di.s appear. I t 1. s a1 s o, I b el 'Ie ve ' a umversa CHAP. XIII. RUDIMENTARY ORGANS. 453 rule, that a rudimentary part or organ is of greater size relatively to the adjoining parts in the embryo, than in the adult; so that the organ at this early age is less rudimentary, or even cannot be said to be in any degree rudimentary. Hence, also, a rudimentary organ in the adult., is often said to have retained its embryonic condition. I have now given the leading facts with respect to rudimentary organs. In reflecting on them, every one must be struck with astonishment: for the same reasoning power which tells us plainly that most parts and organs are exquisitely adapted for certain purposes, tells us with equal plainness that these rudimentary or atrophied organs, are imperfect and useless. In works on natural history rudimentary organs are generally said to have been created "for the sake of symmetry," or in order "to complete the scheme of nature;" but this seems to me no explanation, merely a restatement of the fact. Would it be thought sufficient to say that because planets revolve in elliptic courses round the sun, satellites follow the same course round the planets, for the sake of symmetry, and to complete the scheme of nature? An eminent physiologist accounts for the presence of rudimentary organs, by supposing that they serve to excrete matter in excess, or injurious to the system ; but can we suppose that the minute papilla, which often represents the pistil in n1ale flowers, and which is formed merely of cellular tissue, can thus act? Can we suppose that the formation of rudimentary teeth which are subsequently absorbed, can be of any service to the rapidly growing embryonic calf by the excretion of precious phosphate of lime ? When a man's fingers have been amputated, imperfect nails sometimes appear on the stumps : I could as soon believe that these vestiges of nails have appeared, not from unknown laws |
