Sem'. 5, 1884.] 



KNOWLEDGE ♦ 



193 



and Midlands Railway. (It is worthy of note that the 

 vehicles jointly owned by the English and Scotch companies 

 working the three great routes to Scotland — viz., the East 

 Coast, the West Coast, and the Midland Scotch Joint 

 Stocks — ai-e fitted with the Westinghouse automatic bi-ake.) 

 Most of the companies mentioned use the brake very ex- 

 tensively, and the testimony of Mr. T. E. Harrison (engi- 

 neer-in-chief to the North- Eastern Railway) in his report, 

 previously alluded to, is worth quoting. "There does 

 not appear," he says, " to be any one point in the principle 

 and arrangement of the Westinghouse brake, as now in 

 use, reipiiriog alteration, and it entii-ely complies with all 

 the requirements of the Board of Trade." 



I may add that during three years and nine months 

 there has been an increase in the sales of Westinghouse 

 automatic brakes of 8,276 sets of apparatus for engines, 

 and 49,503 for carriages and waggons, there being alto- 

 gether on the 30th of April last, 11,553 sets for engines, 

 and G3,0G5 for carriages and waggons. 



It only remains for the public to express a forcible and 

 determined opinion on the svibject for the whole of the 

 Companies to adopt this brake. It is better for the public 

 to bring abont the desired change, than to resort to Par- 

 liamentary coercion ; more especially is this the case when 

 it happens that there is only one firm able to do what is 

 required. There are, of course, accidents in which any 

 brake would be useless, such, for example, as the Forth 

 Bridge and the Abergele disasters. The former is too fresh 

 in the minds of the public to need more extensive reference; 

 the latter resulted from some runaway trucks loaded with 

 casks of petroleum making their way down an incline, and 

 meeting with the Irish mail, which was travelling in the 

 opposite direction at full speed. The collision was inevit- 

 able, the casks were burst, the petroleum caught fire, and 

 the flames and smoke enveloped the front portion of the 

 train, stifling or burning every person within the carriages. 



MORE ABOUT SUNFLOWERS. 



By Grant Allen. 



IN order to answer Mr. Paulson's very interesting and 

 suggestive queries about the sunflower, I think 1 shall 

 have to write another short article upon the same subject. 



The tiny drops of viscid liquid upon the ends of the 

 protective bracts which cover the unopened florets while 

 still in their bud condition consist of a resinous inaterial, 

 which can be collected on the finger in suflicient quanti- 

 ties both to show its thickness and to allow one to experi- 

 ment upon its gustatory qualities. Its taste is decidedly 

 nasty, and I have very little doubt it acts as a deterrent 

 to destructive insects, which might otherwise burrow their 

 way among the unopened flowers for the sake of the 

 immature pollen, as we know occurs in many other kinds 

 of composites. On cutting open several heads of sun- 

 flowers I find many small insects (chiefly beetles and 

 weevils) wandering about among the florets in the 

 male, female, and over-blown condition, but not 

 one among the central unopened buds. I am 

 strongly inclined to suppose, therefore, that the 

 latter owe their immunity from premature rifling in 

 great part to the disagreeable sticky secretion. But I 

 observe also that bees avoid the central disk, which 

 seems such a convenient landing-stage, and concentrate 

 themselves upon the two rings of male and female flowers ; 

 and this is obviously beneficial to the plant, since, if they 

 landed first on the centre of the disk, they would carry 

 pollen from the inner male florets to the outer females ones 

 of the same breed, thus defeating the great object of the 



highest sort of cross-fertilisation — impregnation of the 

 stigma l>y pollen brought from a totally distinct plant. 

 The resinous secretion may therefore serve a double pur- 

 pose, first, in protecting the young buds, and, secondly, in 

 compelling bees to alight and visit the flowers in the order 

 most conducive to cross-fertilisation. 



The mechanism for the withdrawal of the anthers and 

 style after their functions have been respectively performed 

 is so minutely curious that I feared to describe it in full, 

 lest it should prove tedious to the readers of Knowledge. 

 Since I am asked for it, however, here it is, as well as I am 

 able to explain it. 



The style, with its two sensitive stigmatic surfaces folded 

 closely together, is enclosed in the united anther tube, and has 

 numerous small hairs, pointing upwards, on its outer sur- 

 face. The pollen-sacs open inward, and fill the hollow 

 cylinder thus formed with shed pollen, before the separate 

 florets open. As each floret matures for its first (male) 

 stage, the style pushes upward, inside the anther-tube, and 

 the hairs on its surface drive the pollen to the top of the tube, 

 where it stands in a little heap, as soon as the flower opens. 

 The filaments are sensitive (a fact which can be tested in a 

 manner I will presently describe), and as soon as the pro- 

 boscis of an insect touches them they contract, thus slightly 

 withdrawing the anther tube, and shedding the pollen over 

 him at the exact right moment to ensure its being 

 employed in fertilising another flower. After the pollen 

 has thus all been shed, the filaments continue still further 

 to contract, apparently by mere fading, till the style 

 protrudes from the top of the anther-sac. The fila- 

 ments, however, are still so elastic that one can pull 

 them out with the finger almost to the original length. The 

 depression of the anthers into the tube of the corolla seems 

 to be aided in part by the unfolding of the style, which 

 now curves over its two branches, thus displaying the 

 receptive stigmatic papill.T, which catch the pollen and 

 induce it to emit pollen-tubes. If the floret is fertilised by 

 a bee, well and good ; if not, the branches of the style bend 

 over until they come in contact with the pollen swept by 

 the hairs of a neighbouring style from a sister floret. They 

 thus secure the second-best sort of cross-fertilisation, that 

 from another flower of the same head. As soon as ferti- 

 lisation has taken place, the curved branches wither, the 

 style shrinks or shrivels just as the filaments had done 

 before, and the entire mechanism is finally withdrawn 

 within the tube of the corolla. At the same time, the corolla 

 as a whole bends outward at the base, becomes humpbacked 

 as it were, so as to turn away from the centre and thus 

 avoid distracting the attention of the insect visitors. The 

 lobes also bend together slightly, as if to deter the bee from 

 trying these already over-blown flowers. The shrinkage in 

 each case seems to me to be merely due to the usual shrivel- 

 ling of all parts which have fulfilled their function, but in 

 the filaments it is greatest on the inner surface, so as to 

 make them bow outward. As long as the style and the 

 filaments are still actively required, they are full of juice 

 and vigour ; as soon as the pollen is shed and the ovary 

 fertilised, they become at once flaccid and contracted. 



In order to observe the sensitiveness of the filaments, 

 take a fully-open sunflower, and select a few florets (with- 

 out removing them from the head) in the highest perfection 

 of the male stage, when the pollen stands in a little heap at 

 the top of the anther tube. Then, with a needle, or, still 

 better, a soft bristle, remove the pollen gently from the 

 summit of the anthers. You will thus be enabled to 

 observe better the after effect. Next, push the needle or 

 bristle down the corolla tube, and gently irritate the base 

 of the filaments, exactly as an insect would do with its 

 proboscis in searching for honey. You will observe in a 



