September 10, 1868. ] 



JOURNAL OF H0RTICULTU1U3 AND COTTAGE GABDENER. 



189 



one desirous of eeeing Mr. Jackman'a collection of Clematis will 

 meet with the Baiiio courtesy that I experienced. — D., Deal. 



NOTES AND GLEANINGS. 



\Vk are informed that at the meeting of the Royal Horticul- 

 tiual Society's Fruit Cummittee, on the tJth of October, two 

 prizes, £3 and £2, will he ollered for the first and second hest 

 collections of Edible Fungi. 



Froji Dr. Hooker's admirable opening address at the 



meeting of the Bhitisii Association fou thk Advancement of 

 Science we extract the following : — 



"The gi'oatost botanical discoveries mado dnrinfr the last ten years 

 have bceu ])liysioIof^ii'al, and I here alludo especially to the series of 

 papers oa the ferlilisatiou of plants which we o»ve to Mr. Darwin. 

 You are aware that this distinguished naturalist, after aecamnlating 

 stores of specimens in peoloj^ and zoology during his circumnavi;:^ation 

 of the globe with Ca]itain Fitzroy, espoused the doctrine of the con- 

 tinuous evolution of life, and by applying to it the princijtles of natural 

 selection, evolved his theory of the origin of species. Instead of pub- 

 lishing these views as soon as conceived, he devoted twenty more years 

 to further observation, stndy, and experiment, with the view of maturing 

 or Fubvei-ting them. Among the subjects requiring elucidation or 

 verification wore many that appertained to botany, but which had been 

 overlooked or misunderstood by botanical writers, and these he set 

 himself to examine vigorously. The first-fruits of his labours was his 

 volume on thu ' Fcrtihsation of Orchids,' undertaken to show that the 

 same jdant is never continuously feriihsed by its own pollen, and that 

 there are special provisions to favour the crossing of iuiUviduals. As 

 his stndy of the British species advanced, ho became so interested in 

 the number, variety, and complexity of the contrivances he met with, 

 that he extended his survey to the whole fnmily ; and the result is a 

 work of which it is not too much to say that it has thrown more light 

 npon the structure and functions of the floral organs of this immense 

 and anomalous family of plants than had been shed by the labours of 

 all previous botanical writers. It has, further, opened u]) entirely 

 new fields of research, and discovered new and important principles 

 that apply to the whole vegetable kingdom. This was followed by his 

 paper on the two well-kno^vn forms of the Primrose and Cowslip 

 {Journal of ih: Linnean Socirtj/ of London, vi., p. 77), popularly 

 known as the pin-eyed and thrum-eyed ; these forms ho showed to be 

 sexual and complementary ; their divers functions being to secure by 

 their mutual action full fertilisation, which he proved could only occur 

 through insect agency. In this paper he established the existence of 

 homomoi-phic, or legitimate, and heteromorphic, or illej^timate, unions 

 among plants, and details some curious ob.servatious in the structure 

 of the pollen. The results of this, perhaps, more than any other of 

 Mr. Darwin's papers, took botanists by surprise, the plants beiug so 

 familiar, their two forms of flower so well known to every intelligent 

 observer, and his explanation so simple. In myself I felt that my 

 botanical knowledge of these homely plants had been but little deeper 

 than Peter Bell's, to whom 



" ' A Primrose hy the river's brim 

 A yellow Primrose was to him, 

 And,— it was nothiug more.* 



*' Analogous observations on the dimorphism of Flax flowers and 

 their allies (Jouni/il o/tJie Lituifan Socut i/ ^ vii., (^0), formed the sub- 

 sequent paper, daring which he maile the wonderful discovery that in the 

 common Flax, the pollen of one form of flower is absolutely impotent 

 when applied to its own stigma, but invariably potent when applied to 

 the stigma of the other form of flower ; and yet both pollens and 

 stigmas of the two kinds are utterly undistinguishable under the highest 

 powers of the microscope. 



" His third investigation is a very long and laborious one (Journal of 

 the Linnean Society, viii., 169), on the common Loosestrife (Lythrum 

 saUcaria), which he showed to be trimorphic ; this one species "having 

 three kinds of flowers, all annually abuntlnntly produced, anil as dif- 

 ferent as if they belonged to different species ; each flower has, farther, 

 three kinds of stamen, differing in form and function. We have in 

 this plant, then, six kinds of pollen, of which five at least are essential 

 to complete fertility, and three distinct forms of style. To prove these 

 various differences, and that the co-adaptation of all these stamens and 

 pistils was essential to complete fertility, Mr. Darwin had to institute 

 18 sets of observations, each consisting of V2 experiments — 21t> in all. 

 Of the labour, care, and delicacy required to guard such experiments 

 against the possibility of error, those alone can tell who know experi- 

 mentally how difficult it is to hybridise a large-flowered plant of simple 

 form and structure. The result in this case, and in those of a number 

 of alhed plants experimented on at the same time, is what the author's 

 sagacity predicted ; iho-rationaJc of the whole was demonstrated, and 

 he finally showed, not only how Nature might operate in bringing 

 these comphcated modifications into harmonious operation, but how 

 through insect agency she does do this, and why she does it too. 



" It is impossible ever to enumerate the many importaut generali- 

 sations that have flowed from these and other papers of Mr. Darwin's 

 on the fertilisation of plants ; some that appear to be commonplace at 

 6xst eight are really the most subtle, and, lik« many other apparent 

 common places, are what, somehow, never occur to commonplace minds ; ' 



as, for instance, that plants with conspicuounly coloured flowerfl, or 

 powerful odours, or honeyed secretions, are fertilised by insects ; oil 

 with inconspicuous flowers, and especially such as have pcuduloos 

 anthers, or incoherent polkn, are fertilised by the wind : whence he 

 infers that, before honey-feeding insects existed, the vegetation of oor 

 globo could not have been ornamented with bright-coloured flowerg, 

 but consisicd of such plants as Pines, Ouks, Grape?, Nettles, &o. 



" The only other botanical paper of Mr. Darwin's to which I can 

 especially allude U that * On tho Habits and Movements of Climbing 

 Plants' [Jonrnui of tlu^ J.iiuifnii fiockty, vol. ix,, p. 1), which is a 

 most elabonito investigation into the structure, modification, and 

 functions of the various organs by which plants climb, twine, and 

 attach themselves to foreign objects. In this ho reviews every family 

 in the vegetable kingdom, aud every organ nsicd by any plant for tha 

 above pui-pQsu. The result places tho whole subject in a totally new 

 light before us. The guesses, crude observations, and abortive ex- 

 periments that had disfigured tho writings of previous observora are 

 swept away ; orjjans, structures, aud functions of which botanists had 

 no previous knowledge are revealed to them, aud the whole investi- 

 gation is made as clear as it is interestinj^ and instructive. 



" The value of these tUscoverics, which add whole chapters to th© 

 principles of botany, is not theoretical only ; already the horticuiturist 

 and flfiriculturist have began to ponder over them, and to recognise in 

 the failure of certain crops the operation of laws that Mr. Darwin 

 first laid down. What Faraday's discoveries are to telegraphy, Mr. 

 Darwin's will assuredly prove to rural economy in its widest sense and 

 most extended application. 



" Another instance of successful experiment in Physiological Botany 

 is Mr. Herbert Spencer's observations on the circulation of the sap and 

 formation of wood in plants [Linnean Transactions, vol. sxv.. p. 405). 

 As is well known, the tissues of our herbs, shrubs, and trees, from the 

 tips of their roots to those of their petals and pistils, are permeated 

 by tubular vessels. The functions of these have been hotly disputed, 

 some physiologists aflirming that they convey air, others fluids, others 

 gases, and still others assignuig to them far-fetched uses, of a wholly 

 different nature. By a scries of admirably-contrived and conducted 

 experiments, Mr. Spencer has not only shown that these vessels a»0 

 charged at certain seasons of the year with fluid, but that they are 

 intimately connected with the formation of wood. He farther in- 

 vestigates the natnre of the special tissues concerned in this operation, 

 and shows not merely how they may act, but, to a great extent, how they 

 do act. As this paper will, 1 believe, bo especially alluded to by tha 

 President of the Biological Section, I need dwell no further on it here 

 than to quote it as an example of what may be done by an acute 

 observer and experimentalist, versed in physics and chemistry, but, 

 above alb thoroughly instructed in scientific methods. 



" Mr. Darwin's recent two volumes ' On Animals and Plants under 

 Domestication,' are a catacomb of data, observations, and experiments, 

 such as assuredly no one but himself could produce. It is hard to say 

 whether it is most remarkable for the number aud value of the new 

 facts it discloses, or for its array of small, forgotten, or overlooked ob- 

 servations, neglected by some naturaUsts, and discarded by others, 

 which, under his mind and eye, prove to be of first-rate scientific im- 

 portance. An eminent surgeon and physiologist (Mr. James Paget), 

 has remarked to me, ajyropos of these volumes, that they exempli^ in 

 a most remarkable manner that power of utihsing tho waste materials 

 of other scieutific men's laboratories, which is a very characteristic fea- 

 ture of their author. As one of iho^G pieces j nut ifcativcs oi his previous 

 work, " The Origin of Species," which have been waited for so long and 

 impatiently, these volumes will probably have more than their due 

 intluence ; for the serried ranks of facts in support of his theories 

 which they present may well awe many a timid naturalist into bolting 

 more obnoxious doctrines than that of natural selection. 



" It is in this work that BIr. Darwin expounds his new hypothealff 

 of Pangenesis, which certainly correlates, and may prove to contain 

 the rationale of all the phenomena of reproduction and of inheritance. 

 You are aware that every plant or animal commences its more or less 

 independent life as a single cell, from which is developed an organism 

 more or less closely similar to its parent's. One of the most striking 

 examples I can think of is afforded by a species of Begonia, the stalks, 

 leaves, aud other parts of which are supeificially studded with loosely- 

 attached cells. Any one of those cells, if referred to favourable con- 

 ditions, will produce a perfect plant, similar to its parent. You may 

 say that these cells have inherited the potentiality to do so ; but this 

 is not all, for every plant thus produced in like manner dcvelopes on 

 its stalks and leaves myriads of similar cells, endowed with the same 

 property of b^^coming such in new plants ; and so on, apparently in- 

 terminably. Therefore, the original cell that left the grandparent not 

 only carried with it this so-callod potentiality, but multipUed it and 

 distributed it with undiminished power through the other cells the 

 plant itself produced ; and so on, for countless generations. What is 

 this potentiality, and how is this power to reproduce thus propagated, 

 so that an organism can. by single cells, multiply itself so rapidly and, 

 Within very narrow limits, eo surely and so intenniuably ? Mr. Darwin 

 suggests an explanation, by assuming that each cell or fragment of a 

 plant (or animal), contains myriads of atoms or geminules, each of 

 which geminules he supposes to have been thrown off from the separate 

 cells of the mother plwut, the geminules having the power of multipli- 

 cation and of circulating throuf-hout the plant ; their future develop- 

 ment he supposes to depend on their aflijiity for other partially de- 



