Maj' 7, 1 8 74 J 



NATURE 



The Fertilisation of Fumariaceae 



It was with great pleasure and interest that I read the com- 

 munications from Mr. Darwin and Dr. Hermann Miiller in 

 Nature, vol. i.x. p. 460. 



It so happens that, since writing the note on the tardy and 

 apparently useless assumption of colour by Fiimaiia caprco- 

 lala ■vRT.pilliiiijlo.'ti, I have chanced to see the flowers of this 

 plant visited, on two occasions, by a bee in the daytime. 



This insect was, on both occasions, I believe, a mason-bee, 

 and certainly neither a hive nor a Immble bee, and, as it con- 

 fined its attentions to this one variety of fumitory, and was 

 engaged for some time at its work, I had a favourable oppor- 

 tunity of watching the mode of operation. 



The bee ranged from plant to plant, but, in every case, would 

 only alight on and suck those flowers which, though still white, 

 had assumed the horizontal position, these flowers alone affording 

 a comfortable landing-stage for the insect. 



The bee then clasped the lower part of the tube with its feet, 

 and prized open the flower by thrusting its sheathed proboscis 

 underneath the upper petal, when the tube split lengthwise, and 

 gaped widely open, the style and stamens rising up and emerging 

 Irom the cap formed by the inner petals, much as they do Irom 

 the keel in many papilionaceous flowers, and rubbing against the 

 underside of the bee's body. 



I may observe that it is precisely in the short period during 

 which the flower maintains itself in the horizontal position that 

 the emission of pollen takes place, and this coincidence of the 

 plant bidding for the visits of insects at that particular moment 

 has much the appearance of special adaptation. 



But an examination of the flowers certainly shows that they 

 are cap.able of self- fertilisation, and Dr. Hermann Miiller tells us 

 that Dr. Hildebrand states that this is habitually the case in 

 /•: capfcohil.}. 



I regret that I am only acquainted with Dr. Hildebrand's 

 paper through a review which appeared in the Bulletin of the 

 Socicte Botanique de France, where but few of the details are 

 given. 



I have not paid special attention to the structure and habits of 

 the Fitmariaccit, and I am therefore unable to say vihether the 

 plant to which I have alluded is commonly visited by insects in 

 the daytime, or whether, as Mr. Darwin suggests, its flowers, 

 the nearly white colour of which would render them peculiarly 

 conspicuous in the dusk, may not prove especially attractive to 

 moths and other night-fliers. 



While watching the bee whose operations are described above, 

 I noted with interest that it confined its attention exclusively to 

 plants of this single variety of fumitory, winding its way through 

 flowering masses of other fumitoiies and v/eeds. 



In the same way a honey-bee, at the same spot on a later day, 

 exc usively visited the wild mignonette (Reseda phyteiima), 

 passing by the fumitories, marigolds, &c. 



J. Tr.vherne Mocgridge 



Maison Gaslaldy, Mentone, April 20 



Allow me shortly to resume the different views which have 

 been proposed in your columns, as giving a possible explana- 

 tion of the fact that the flowers of F. pallidiflora attain their 

 brightest colouring when the time for fertilisation has passed, and 

 to point out tlie obsei-vations indispensable to be made, i" order 

 to ascertain which of the proposed views is right, i- It is 

 possible that nocturnal Lepidoptera are the fertilisers of the 

 iumitoiy ; in this case it would be most probable that the pale 

 colour of its flowers has been acquired by natural selection, pale 

 flowers being most conspicuous in the dusk. 2. Diurnal insects 

 may be the fertilisers, and the pale hue may be sufficiently con- 

 spicuous or even more attractive for Ihem than the brighter one. In 

 this case, also, the former must be considered as acquired by natural 

 selection ; the latter, on the contrary, as in the first case, merely as 

 the result of chemical processes. 3. Under the same supposition of 

 diurnal insects being the fertilisers, it is possible that the older 

 flowers, by their brighter hue, serve to attract insects to the younger 

 and paler ones ; in this case the bright hue of the older flowers may 

 be looked upon as acquired under the inflitence of natural selec- 

 tion, the pale colour of the younger flowers at the same time 

 being useless. 4. It is possible that self-fertilisation is the rule 

 with the flowers of this fumitory, and that cross-fertilisation by 

 insects takes place only very exceptionaUy ; in this case not only, 

 as in No. 3, the p.aler colour, but also the brighter one would be 

 nearly independent of the influence of natural selection. In 

 order to decide definitely which of these views is right, it is 



indispensable to watch perseveringly the flower of this plant, and 

 to ascertain what kind of fertilisation naturally takes place. 

 In case diurnal insects should prove by direct observation 

 to be the fertilisers, it would be possible to decide whether 

 supposition 2 or 3 is correct, by removing from many specimens 

 every older flower as soorr as its colour begins to grow brighter, 

 and by observing whether these specimens or those with older 

 and brighter flowers are more frequently visited by insect.s. 



It would be a great pleasure to me to make these observations, 

 but I do not know whence seeds of Fumaiia pallidiflora can be 

 obtained. Perhaps some reader of this letter may be good 

 enough to give me information on this point. 



Lippstadt, April 28 IIerm.'^nn Muller 



Ms. Comber's suggestion {vol. ix. p. 484) that the coloured 

 flowers ai Fumaria attract insects to the uncoloured ones is very in- 

 ingenious. Supposing that they are cross-fertilised, the case of 

 Poinseltia is very pertinent, and is enforced by that of Dalc- 

 chatnpia, also euphorbiaceous, in which the bracts, a beautiful rose 

 coloitr before fertilisation, gradually assume afterwards the same 

 green hue as the foliage when the bright colour is no longer 

 needed. The chemical changes that take place in the flower at 

 and after the period of its complete expansion must necessarily 

 be complex, as well as varied in different cases. Rapid oxidation 

 is probably one very effective agent in producing them, but the 

 results will necessarily depend on what is operated upon. 

 Hibiscus inutabilis is white in the morning, deep red by night. 

 Species of Lantaiia, like Myosotis versicolor, pass through a 

 whole series of colours as they expand. On the other hand all the 

 beautiful species of Franciscca rapidly lose the tints with whiclr 

 their flowers open, and become nearly white. The final stages in 

 the life of all the parts of the flower which are not accessory to the 

 formation of the fruit are more or less processes of decay, and there 

 is no absolute law that these should always be accompanied by in- 

 conspicuous or displeasing tints. The white flowers of Calanthe 

 veratrifolia blacken when they are bruised ; on the other hand, 

 according to Kingsley, the crimson flowers of CoKroiipila giiia- 

 nensis turn blue when torn, as the pulp of the fruit is also krown 

 to do on exposure to the air. In the same way some fungi ex- 

 hibit when bruised striking tints which yet can be of no service 

 to them. Agaricus georgincc changes from snow-white to blood- 

 red wherever it is touched, and the white flesh of Boletus cvanes- 

 cens when broken changes instantly to the "most beautiful azure 

 blue." 



In fact if a chemical change is set up — if it produces a change 

 of lint at all — it must sometimes produce a pleasing one ; that it 

 should do so is not necessarily advantageous to the plant, though 

 open to be taken advantage of by it. 



W. T. TmsEL'ioN Dyer 



Fertilisation of Corydalis claviculata 



With regard to the flowers of Corvdalis claviculata (of the dis- 

 co .'ei-y ofjwhich species in this neigh jourhood I have se it ajnotejto 

 the 'journal of Botanv), I think .\jr. Bennett (vol. i.x. p. 484) will 

 find his suspicion that the stjies may have been broken ott m dis- 

 secting to be correct. This may easily be shown by floating off 

 in water the pe'als, &c., of a withered flower, in which the pro- 

 c;is of fertilisation has been completed, when the style will be 

 seen adhermg to the ovary, though the gentlest touch will be 

 sufficient to separate it. In the bud the anthers cover the stig- 

 ma, but at the time of maturity the latter projects .slightly, so 

 that it; would be first touched by the proboscis of an insect. I 

 suspect that it is also slightly protogynous, though self-fertilisa- 

 tion may probably be of frequent occurrence. The manner in 

 which the style is embraced by the stamens and petals protects 

 it from too rough a shock from the struggles of insects in the 

 narrow entrance to the flower. I have not, how ever, observed 

 them to visit it. W. K. Hart 



Kilderry, co. Donegal, April 28 



Lakes with two Outfalls 

 SiN'CE writing my letter of April 24, with which I forwarded 

 a copy of the new Inch Ordnance map of Arran, I have received 

 other copies from Mr. Stanford, showing, as I presume, that 

 the early copies of General Sir H. James's admirable work have 

 been revised. For, besides the elaborate system of contour lines, 

 which did not appear in the first copies, /tcw outlets are given to 

 Loch-na- Davie, instead of one only. So that, as to the "matter 



