OCR Text |
Show 6 INTRODUCTORY REMARKS. CJJAP. I. and Hermann Muller,* and numerous shorter papers, have been published. A list would occup~ sever~l pages, and this is not the proper place. to g1ve then titles as we are not here concerned with the means, but w' ith the results of cross-fertilisation. No one who feels interest in the mechanism by which nature effects her ends, can read these books and n1emoir without the most lively interest. From my own observations on plants, guicl d to a certain extent by the experience of the bre ders of animals, I became convinced many years ago that it is a general law of nature that flowers are adapted to be crossed, at least occasionally, by pollen from a distinct plant. Sprengel at times foresaw this law, but only partially, for it does not appear that he wa aware that there was any difrerence in power between pollen from the same plant and from a distinct plant. In the introduction to his book (p. 4) he says, as the s x s are separated in so many flowers, and as so many other flowers are dichogamous, "it appears that natur has not willed that any one flower should be f rtilised by its own pollen.''' Nevertheless, he was far from }~eepin g this conclusion always before his mind, or he did not * .Sir JolJ_n Lubbock has given an mtcrestmg summary of the whole subject in his 'British 'Wild ]'lowers considered in relation to Insects,' 1875. Hermann MUller's work 'Die Befruchtung cler Blumen durch Insekteu,~ 187R contains an immense numb~r of ori~i11~l observations and generalisatiOns. It is, moreover, invaluable as a repertory with l'eferencrs to almost everythin()' which hAs been published on th~ subject. His work differs from that of. all oth~rs in specifying what klnds of msects, as far as known, vi it the flowers of each species. He likewise enters on new ground, by showing not only that tlowers nre adapted for th ir own good to the vitsits of certain in.·eds ; but that the ilLx~rts themselvt s are excellently adapted for procuring nectar or pollen from certain flowers. The vnlu of H. Mi.iller's work can hardly be over-estimated, a11d it i~:~ nmel1 to be desired that it slloultl b tmn - lated into English. Severin Axell's work is written in Swoc.lisJ1, so that I have not been able to read it CHAP. I. INTRODUCTORY REMARKS. 7 see its full importance, as may be perceived by any .. one who will read his observations carefully ; and he consequently mistook the meaning of various structures. But his discoveries are so numerous and his work so ~xcellent, that he can well afford to bear a small a1nount of blaine. A most capable judge, H. l\iiiller, likewise says:* "It is remarkable in how very 1nany cases Sprengel rightly perceived that pollen is necessarily transported to the stigmas of other flowers of the same species by the insects which visit them, and yet did not imagine that this transportation was of any service to the plants themselves." Andrew Knight saw the truth much more clearly, for he remarks,t "Nature intended that a sexual intercourse should take place between neighbouring plants of the same species." After alluding to the various means by which pollen is transported from flower to flower, as far as was then imperfectly known, he adds, "Nature has something more in view than that its own proper males should fecundate each blossom." In 1811 Kolreuter plainly hinted at the same law, as did afterwards another famous hybridiser of plants, Herbert.t But none of these distinguished observers appear to have been sufficiently impressed with the * 'DiP Befruchtung cler Blumen,' 1873, p. 4. His word:; are: "Es ist merkwti.rdig, in wie zahlreichen Fallen Sprengel richtig erlmunte, class durch <lie Besuchenden Insekten der Bll.lthenstaub mit N otlnvendigkeit auf die N arben nnderer Bliitlten derselben Art i.ibertragen wird, ohne auf die Vermuthung zu kommen, dass in diesc:::r Wirkung der N utzen des Insektenbesuches fLir die Pflanzen selbst gesucht werden miisse." i" 'Philosophil'al Transactions,' 1799, p. 202. t Kolreuter, ' 1\Icm. de l' A cad. de St. P etersbourg,' tom. iii. 1809 (published 18ll), p. 197. After silowing how well the Mal vaces.e are adapted for cross-fertilisation, l1e asks," An id aliquid in recebSU habeat, quod hujuscemodi .Bores nunquam proprio suo pulvere, srd semper eo aliarum sure speciei impregnentur, merito quroritur '? Certe natura nil facit fru stra." Herbert, 'Amaryllidacem, with a 'rreatise on Cross-bred Vegc· tables,' 1837. |