344 



SCIENCE- GOSSIP. 



many of these catkins were expanded upwards of 

 three inches in length in this valley at an elevation 

 of about five hundred feet ; being in fact so abundant 

 I gathered a few, and subjected them to chemical 

 analysis. The fresh catkins contained (58 per cent, 

 of water, 29-8 organic matter, and 2-2 ash. The 

 dried substance contained about 2 per cent, wax, 

 fat, resin, and a trace of carotin, about 16 per cent, 

 tannin, phlobaphene, rutin, etc., over 10 per cent. 

 sugar, mucilage, etc., 29 fibre, and 6-7 ash. The 

 remarkable feature about the constituents was the 

 considerable quantity of rutin, tannin, and phloba- 

 phene, and I may say that the oxalate of calcium 

 extracted by dilute hydrochloric acid yielded 

 crystals of a size and beauty unparalleled in my 

 experience. Every effort was made to detect 

 starch, but none was found ; nor were fruit-sugar 

 or citric acid discoverable in the aqueous or alco- 

 holic extracts. The proportion of mucilage was 

 very large, but the albuminoids seemed rather 

 scanty. The ash of the catkins contained about 

 31 "6 per cent, soluble salts, 22 potass and soda, 

 7'4 silica, 20-2 oxide of calcium, and 10'2 phos- 

 phoius (PnOj). According to De Planta dried 

 hazel pollen contains 5 per cent, starch and 31 '63 

 albuminoids, also 7 to 8 cane sugar, biit no 

 glucose. I prepared some of the pollen grains as 

 carefully as possible, and applied the iodine test 

 under the microscope, but failed to detect any 

 trace of starch. I may add that the primrose tint 

 of the catkins is due to a trace of carotin, and the 

 brownish shades to dehydrated tannin. — (-0^'.) 

 P. Q. Keegan, Patterdale, Westmorland. 



A Maltese Plant. — There are flowering in 

 Malta at the present time some small blue flowers, 

 of which I do not know the name. A curious 

 thing occurred in connection with one of these 

 which interested me, so I thought perhaps I might 

 get an explanation by addressing this to SciENCE- 

 GOSSIP. I had picked the plantlet by the root and 

 brought it on board, and put it into a little test-tube 

 with some water to grow. One flower came out 

 and expanded well, but was half closed the next 

 morning, so I put it in the sun to see if it would 

 expand again. This seemed to have no effect, so I 

 concentrated the rays of the sun on it by a magni- 

 fying glass in such a way that the size of the 

 circle of rays was about one-sixth the size of the 

 glass, or, say, six times the strength of the sunlight, 

 and the flower was inside the focus of the glass. 

 For about a minute nothing happened. At the end 

 of that time I was astonished- to see the corolla 

 entire, carrying with it, I afterwards found, the 

 stamens, make a sudden and violent start away 

 from the calyx and stalk. I still kept the light on 

 it, and after about three seconds the corolla, with 

 another, most sudden jump, conveyed itself clear of 

 the calyx and stalk altogether, and fell down clear 

 of the plantlet at some little distance on the table 

 by its side. I should be most interested if anyone 

 could give me an explanation of this effect of 

 light on the plant. — Lieut. B. P. Weston, JI.3I.iS. 

 " Pimia" Mediterranean Sqnadron. 



[Judging from your sketches enclosed and 

 description, your Maltese plant is an AnagalUs, 

 probably .4. coerulea. Its near ally, the A. arvensis, 

 is frequent in fields and waste places in this country, 

 and from its habit of expanding its flowers only in 

 clear weather it is known as the "Poor Man's 

 Weather-glass." A. cocrulea, the blue pimpernel, 

 occurs in many places in Britain. — J. A'.] 



Protective Characters in Plants. — In an 

 article in a contemporary the Rev. A. S. Wilson 

 recently treated of protective characters in plants. 

 As an example, the resemblance between the white 

 dead nettle (Laiiiinm^ alhuni) and the stinging- 

 nettle (JJrtica dioica) is given. In order to prove 

 that a case of so-called mimicry is really of protec- 

 tive value three things are required : — (1) It must 

 be shown that the resemblance is suificiently close 

 to deceive those animals interested in the mimick- 

 ing species. (2) It must be proved that the imitated 

 species is really protected. (3) That the mimicking 

 species escapes from those enemies which destroy 

 the related, non-mimicking species. As i-egards 

 the first point, it may be admitted that there is a 

 general superficial resemblance between the two 

 species. Is it sufficient, however, to deceive any 

 animal interested in the dead nettle as a source of 

 food supply 1 I think not. My daily bread does 

 not depend on my ability to distinguish them, yet 

 the difference is quite obvious to me even at a little 

 distance. Would even the most amateur of 

 botanists admit that he could not readily detect 

 the difference 1 What, then, if our daily business 

 was to discriminate between them ? They would 

 have, for us, less resemblance than an apple has to 

 a gooseberry. So it must be with those animals 

 which depend on the dead nettle as a source of 

 food supply. Again, we all know how much keener 

 the scent of most animals is than our own, and 

 Lamium album has a scent totally different from 

 that of Urtica dioica. While as regards insects, it 

 has been shown that they are much more probably 

 attracted to plants by scent than by sight. It 

 seems to me, then, that as regards the first point 

 the case breaks down. Lavdum alhnni is not 

 sufliciently like Urtica dioica to deceive any of 

 its enemies which might conceivably be afraid of 

 the latter. As regards the second point, Urtica 

 dioica, in spite of its sting, is one of the most per- 

 secuted of plants. It Is the ordinary food of the 

 caterpillars of three common butterflies, the red 

 admiral, the peacock butterfly, and the small 

 tortoiseshell. The painted lady and the comma 

 butterfly also sometimes lay their eggs on it, as do 

 several species of Plusidae and other lepidoptera 

 heterocera. The nettle is no more protected against 

 these caterpillars than the cabbage is against the 

 " garden white " butterflies. Nettles are also 

 attacked by gall-flies ; browsing animals occasion- 

 ally eat them ; snails also consume them. Against 

 what, then, is the nettle i^rotected? As regards 

 the third point, I am not prepared to iDrove a 

 negative. It is for those who call the resemblance 

 of Zamium alivm to U'rtica dioica a protective 

 character to bring forward evidence, if there is 

 any. I think, then, I have shown that the re- 

 semblance is not sufliciently strong to deceive an 

 interested enemy, and that the imitated species is 

 not reall}=' protected. My acquaintance with the 

 literature of the subject and a study of those cases ' 

 which I have been able to examine for myself 

 lead me to conclude that this apjjlies to a large 

 number of cases of mimicry and protective cha- 

 racters. Let me give one or two illustrations. On 

 the river Amazon Mr. H. W. Bates met with a 

 moth resembling a humming-bird. This is what 

 he says about it : " Several times I shot by mistake 

 a humming-bird hawk-moth instead of a bird. 

 This moth {Macroglossa titan) is somewhat smaller 

 than humming-birds generally are, but its manner 

 of flight and the way it poises itself before a flower 



\ 



