March 30, 1876] 



NATURE 



427 



thought of introducing the work into school use on the strength 

 of one or two hastily written commendations of it, will be in- 

 duced in consequence of what we have written, to examine the 

 work for himself. We feel confident that any competent 

 geometer who opens the book at almost any page, will eadorse 

 our criticisms, and say " the half v;as not told." In brief, the 

 definitions are faulty, the enunciations are faulty, the proofs are 

 faulty, and the typography is fauUy ; if these things do not make 

 a bad book we do not know what does. The defence is, "if 

 the enunciations are loosely and inelegantly worded, Amiot must 

 bear the blame which atuches in a greater degree to our trans- 

 lations of Euclid," Alas ! poor Amiot ! thi$ is an unkind cut, 

 Mr. Morell ! R. TuCKER 



March 6 



Bullfinches and Primroses 



I HAVE a bullfinch which was hatched last summer after prim- 

 roses were over. They were therefore quite new to him when I 

 offered him the first I could get this season. He pulled it to 

 pieces quite indiscriminately, biting stalk, flower, or calyx quite 

 indifferently, and the same with a few more which were given to 

 him at the same time. But since then he has often had a few at 

 a time, perhaps twenty or thirty in all, and he now almost always 

 bites out the lower part of the calyx, as described in Nature, 

 vol. ix. p. 482. Sometimes he bites a little too high up, but 

 almost instantly tries again with better success. When that 

 part is eaten he attacks the stalk rather than the corolla. 



Last spring I offered primroses to four bullfinches belonging 

 to friends. Not one seemed to pull the flower to pieces accord- 

 ing to any method. Two of them I saw only once. Another 

 (an old bird and somewhat shy), after being supplied with the 

 flowers for several days, seemed as unskilful in picking out the 

 tit bit as he was at first. The fourth was a young bird. His 

 mistress was called away before she had heard what was the 

 peculiarity for which I was watching. A few days later she told 

 me she had been giving him primroses in the meantime, and had 

 noticed that he ate only the green part. In those few days he 

 had learnt the art of primrose eating, not indeed quite perfectly, 

 but wonderfully well considering how little practice he had had. 



C. A.M. 



Seasonal Order in Colour of Flowers 



It seems that Mr. Thiselton Dyer has thought fit to con- 

 clude the different observations made on this interesting subject 

 by copying a part of Sachs's "Text-book." He will, I hope, 

 allow me to point out to him the latest researches respecting the 

 influence of light on the colour of flowers, published by E. 

 Askenasy, in the Botanische Zeitung, 1876, Nos. i and 2. This 

 author made experiments with several flowers which had suffi- 

 cient food at their disposal, and found that some of his flowers 

 changed their colour when placed in the dark, while it was not 

 so with others. Therefore it cannot be said that light has no 

 influence. The cause of this difference, observes the author, has 

 as yet not been explained ; other experiments will have to be 

 made to clear up this point 



I think the colour of most flowers is a thing that by con- 

 tinued inheritance during a very long lapse of time has become 

 almost constant, and cannot be changed in a few weeks or 

 months. Long- continued experiments with the same flowers 

 and their offspring would, perhaps, show more considerable 

 changes than Askenasy found. 



So much for the point referred to by Mr. Dyer. 



As to the seasonal order itself, a continuation of Mr. Alex- 

 ander Buchan's observations would be necessary, and probably 

 also experiments with the several parts of the spectrum to which 

 the flowers are to be exposed. 



As this letter was written, I read that of Mr. Wm. Ackroyd 

 (Nature, vol. xiii., p. 366) ; doubtless every one will expect 

 with great interest his following note. J. C, CoSTERUS 



Amsterdam 



Plant Fertilisation 



Some short time since I observed a rather curious case of 

 plant fertilisation through the medium of insects, and thinking — 

 as the subject is one which is attracting much attention Irom 

 botanists at present— it might be interesting to some of your 

 readers (more especially perhaps as occurring in this remote [..art 

 of the world), I take the liberty of forwarding you the particu- 

 lars in the hope that you can find a comer for them in your 

 yalijable journal. 



Growing rather abundantly just on the coast here is a small 

 shrub belonging, I believe, to the sub-order Coffeae, having 

 numerous small greenish flowers, the interior of the corolla tube 

 filled with silky white hairs, and the style bent in a peculiar 

 manner, so as to bring it to one side of the tube. I observed 

 the anthers dehisce before the flower buds open covering the stig- 

 matic surface (which is simply a thickened continuation of the 

 style) with pollen. I noticed that all the individuals of this 

 species of shrub were visited by a kind of ant in large numbers, 

 and as soon as a flower opened they began pulling out the hairs, 

 lining the corolla tube, and often biting off the stamens also, in 

 order to clear a way down to the nectar contained at the bottom 

 of the tube. In doing so they often support themselves by 

 clinging to the pollen-covered style with their posterior legs. 

 The bend in the style which brings it to the side of the corolla 

 tube prevents it from being an obstruction while they are obtain- 

 ing the nectar, although, so eager are they to get it even to the 

 last drop, that in a few old flowers I noticed even the style 

 removed. The pollen keeps dry for a considerable time, so that 

 cross-fertilisation is effected by the removal of pollen from the 

 stigma of one flower to that of another. 



We have here, therefore, several adaptations of structure and 

 habit to ensure that end. The deluscence of the anthers while 

 in the bud removes the pollen from a part of the flower where it 

 would in all probability be wasted (when the ants bite off the 

 anthers) to another part, where by a peculiarity in its structure, 

 viz., the bend in the style, it is protected and transferred to 

 other flowers. The hairs in the corolla-tube, by rendering the 

 approach to the nectar difficult, and thus making the use of the 

 style as a support needful, also increase the chances of cross- 

 fertilisation. M. S. Evans 



Durban, Natal, South Africa, Jan, 25 



The Visibility of Mercury 



Perhaps some of your readers may, like myself, have been 

 struck with the remarkable brilliance of Mercury to the naked 

 eye on the evening of January 26. I scarcely ever remember to 

 have seen the planet so well deserving the epithet (TTi\0tav. 

 Since April, 1858 I have noticed it twenty-one times with the 

 naked eye at its evening apparitions. It seems difficult to re- 

 concile the liment of Copernicus that he would die without see- 

 ing Mercury with the accounts of his life. The common reason 

 given is, that it was always enveloped, to him, amid the vapours 

 of the Vistula, But he did not pass all his life in that part of 

 Europe. At one time he went t9 Bologna and stayed with 

 Dominic Maria, a professor of astronomy in that place. After 

 this he proceeded to Rome, where he was made professor of 

 mathematics, and where we find him actually engaged in making 

 observations about the year 1500. 



The amateur may look out for Mercury near the western 

 horizon, after sunset, about the following dates : — 1877, Jan. 10, 

 April 29; 1878, April 10 ; 1879, March 26 ; 1880, March 7 ; 

 18S1, Feb. 20; 1882, Feb. 2; 1883, May 6; 1884, April 18; 

 1885, March 31 ; 1886, March 15. 



Tycho Brahe, who could not tiave enjoyed a very favourable 

 latitude for picking up the planet, gives us the following notes 

 in his "Historia Celestis" : — 



1585, Nov, 15. — " Apparuit hoc tempore matutino ^ tanquam 

 rubricunda quaedam steLla secundae magnitudinis et mediae, quasi 

 2 et I magnitudinis." 



1590, March i. — " ^ adamodum apparenter videbatur, instar 

 stellarum primae magnitudinis, adeo ut eam, quae in dextro 

 humero Orionis est, magnitudine visibili repraesentaret. Si 5 

 diametrum visibilem feceris 2^', non inconvenienter se habebit, " 



1596, March 15. — " Erat hac vespera apprime serenum et 

 mediocriter tranquillum. ^ hac vespera satis fuit conspicuus 

 quippe cujus quantitas stellam inter primae et secunda: magni- 

 tudinis referebat." 



Measurements of the diameter of the planet are best obtained 

 when it is seen in transit on the sun, of which there will be a 

 very favourable opportunity for several hours on May 6, 1878. 

 After this, it is doubtful whether we shall see Mercury on the 

 sun again this century in England, as he passes off the solar disc 

 on May 10, 189 1, about half-an-hour after sunrise, and on Nov. 

 10, 1894, the ingress of the planet is only a few minutes before 

 suQset. For a transit to be seen thoroughly from this cotmtry 

 we must wait till Nov. 12, 1907, and Nov. 6, 1914, both of 

 which will be visible throughout here. 



Samuel J. Johnson 



Upton Helions Rectory, Crediton, Feb. 21 



