190 



HARDWICKE'S SCIENCE-GOSSIP. 



[Aug, 1, 1SG9. 



Sundew. — I read with some interest the answers 

 of your correspondents to Mr. Spicer's inquiry re- 

 specting the irritability of the leaves of the Sundew 

 (Science-Gossip, April and May, 1S69), and I 

 would be glad if you would insert a few lines from 

 me in confirmation of this singular phenomenon. 

 None of your correspondents seem to have person- 

 ally observed the act of capture of a fly, and the 

 mere fact of , adhesion of small insects to the 

 glutinous secretion on the hairs of the leaves is only 

 what might naturally be expected, and is quite in- 

 dependent of the existence of any true irritability 

 whatever, the possession of which by the species of 

 Drosera is the point of interest. Like Mr. Spicer, 

 my attention was attracted in the summer of 1863 

 to the passage in Withering's Botany describing 

 the observations of Roth, Whately, and Gardom on 

 this subject. Many authors do not allude to the 

 matter at all ; but Loudon, in his " Encyclopaedia," 

 remarks of the Drosera that "the leaf-hairs are 

 very irritable, and close upon small insects that 

 touch them, after which the leaf itself bends, and 

 holds the dead insect imprisoned." My own obser- 

 vations, made in the bogs of Longford and elsewhere, 

 are in accordance with Roth and Whately's experi- 

 ments. In the Drosera longifolia especially, I saw 

 a great number of the leaves inflexed, and with the 

 hairs turned in, and every one of them contained 

 some irritant substance, generally the dead body of 

 an insect. On one occasion I was fortunate enough 

 to witness the remarkable sequence of movements 

 from the moment that an unlucky midge alit on the 

 tempting but treacherous trap. The movements 

 commenced in about ten. minutes, and it was a 

 curious sight to watch the elegant little hairs curv- 

 ing gradually from base to apex till they met in the 

 centre, locking together, like minialure fingers, and 

 thus securely imprisoning the poor captive. His 

 struggles only served to increase the number of, and 

 to strengthen his bonds. Mechanical irritation of 

 the upper surface of the leaf will also cause the 

 hairs, and finally the leaf itself, to bend inwards and 

 downwards, but the time at which this result hap- 

 pens, after the application of the stimulus, seems to 

 have some connection with the state of the weather, 

 for the experiment succeeds best on a warm, sun- 

 shiny day. — Walter G. Smith, Dublin, July, 1869. 



Skylark (Alaudaarvensis). — During the present 

 summer I have frequently noticed a skylark singing 

 while perched on the edge of a notice-board stand- 

 ing in a neighbouring wheat-field. I have as often 

 seen him standing on a post belonging to the fence, 

 where he sings as merrily as if it were " from his 

 watch-tower in the skies." I have never before 

 known the lark to siug except on the wing ; even 

 the caged bird will often manifest his desire to be 

 " at heaven's gate," by singing with fluttering and 

 expanded wings. I have seen the same skylark 

 sing while ascending, in fact he seems to accomo- 

 date himself to either circumstance. — J". B. W. H., 

 Wolverhampton. 



I have seen larks singing whilst perched very 

 often.— B. II. 



Macgillivray writes of a lark singing on a twig. — 



s. a. 



A Curious _ Martin.— Amongst the flock of 

 Hirundines which annually breed under the caves of 

 our buildings has arrived a rara avis, which con- 

 sorts with a common martin (Hirundo urbica), but 

 is quite different in colour, being of a brownish 

 black with no white on its body. Its habits, forma- 



tion of nest, sound of voice, mode of flight, &c, are 

 precisely similar to those of its neighbours, but, 

 unlike them, it commenced the business of nidifi- 

 cation almost on its first arrival ; I therefore con- 

 cluded that it must be a variety of the common 

 martin and not a distinct species. It was thought 

 by some at first that it was the Hirundo purpurea of 

 America ; but the smallness of the bird, coupled with 

 the dissimilarity of colour, is conclusive evidence 

 that such a surmise must be erroneous. — 6?. B., 

 Hereford. 

 [Is it a Swift ? ] 



Glowworms. — Many readers of Science-Gossip 

 may like to know that these pretty little creatures 

 will live and thrive in a town garden. I turned 

 several out in our garden here, and there is quite a 

 little illumination from them every warm night. 

 They keep to the exact spot in which I turned them 

 out among stone-crop and ferns, which I keep well 

 watered, as the glowworms are most luminous on 

 clamp nights. — W. B. Tate, 4, Grove Place, Denmark 

 Hill, 



Abnormal Erica. — I send you a specimen of a 

 curious abnormal form of Erica tetralix, which I 

 have never observed before. The corolla is divided 

 into a number of separate petals. This condition 

 was not confined to one solitary spray. There is a 

 little clump of it, mixed up in a larger clump, 

 bearing flowers of the normal form, and the con- 

 trast between the two is very striking. It is 

 growing on the side of Beacon Hill in Charnwood 

 Forest.— Frederick T. Mott. 



[Not only is the corolla composed of separate 

 petals, as stated by our correspondent, but there are 

 other changes in the specimen forwarded ; such as 

 increased number of petals, intermediate forms 

 between petals and stamens, adhesion of stamens 

 to styles, open carpels from non-union of the edges, 

 and other indications of a tendency to become 

 " double." The double variety in cultivation no 

 doubt originated from a specimen like that for- 

 warded by our correspondent. — 31. T. M.~\ 



Blood. — I beg to thauk Mr. Lewis for his para- 

 graph on blood, and what he there states seems to 

 me to confirm my ideas about the globules. The 

 difference in size may he a fatal objection, though I 

 think the red globules are not always of precisely the 

 same size. Now Mr. Lewis says that a " high author- 

 ity says that in the higher mammalia the globules 

 without colour exist in a smaller proportion to what 

 they do in man." May we not reckon animals in 

 general more healthy than man ? and then in cases of 

 anaemia, and where weakness in general exists in 

 man, the colourless globules increase in number, 

 and the red ones are not so brightly coloured. In 

 fact, the health has a great influence upon the state 

 of the blood, or, perhaps, we might more properly 

 say the state of the blood has a great effect upon 

 the health. I see most writers consider the globules 

 to be of two distinct kinds, though 1 do not think 

 they satisfactorily point out their different uses. 1 

 do not pretend to argue the point, as I have nor 

 sufficient extent of observation ; but I. cannot help 

 thinking when I read about the blood, and look at 

 it, that the globules are really all of one nature, and 

 that the oxygen in the air acts upon them in some 

 way wdiich causes the greater part to be coloured, 

 and that in proportion as this is done, so the general 

 health and strength are increased, and that where 

 the contrary happens, so weakness of some kind 

 exists. — E. T. Scott . 



