HARDWICKE'S SCIENCE-GOSSIP. 



187 



■ — 1. True Rapbides, needle-like, occurring loosely 

 iu bundles ; 2. Long crystal prisms, with angular 

 shafts, regularly separate, or only two or three 

 soldered together ; 3. Short prismatic crystals, 

 more or less square ; 4. Spbseraphides, mostly of a 

 rounded figure, either smoothish or stellate on the 

 surface. The physiological significance of plant- 

 crystals had been described at former meetings 

 of the Society and elsewhere. The taxonomic im- 

 port of the true Rapbides is enhanced by the fact 

 that they are present in every stage and state of 

 the plant, from the cradle to the grave of the 

 species. 



" Pyrethrum ixodorum. — A double variety, 

 having a multiplied radius and an obliterated con- 

 tracted disk, was found iu Norfolk by the late Mr. 

 Crowe."— (Smith's E. F/., vol. iii.) A plant, exactly 

 similar to the one above described by Smith, who, 

 so far as I am aware, is the only author who men- 

 tions such an occurrence, was found in my parish a 

 week or two ago. The ray florets are in a triple 

 series'; those of the disk reduced to a few brown 

 scales, the receptacle quite flat. One great differ- 

 ence from the type also is, that the teeth of the ray 

 petals are enormously lengthened, so as to give the 

 flower a jagged appearance. Unfortunately, there 

 can be no ripened seed, so the plant cannot be per- 

 petuated. — R. V. 



Living Vegetable Cells imitated. — A recent 

 number of Der Natursforscher gives an account of 

 experiments made by Herr Moritz Traube on what 

 he calis " inorganic cells," which were suggested 

 by Prof. Graham's discoveries in dialysis. If a 

 drop of gelatine solution is acted upon by gallic 

 acid, so that a film of a leathery subs' ance is formed 

 round it, au artificial cell is produced; and this 

 when placed iu a weaker solution of gelatine will 

 swell and exhibit a physical growth through the 

 eudosmose that takes place. Cells with these arti- 

 ficial membranes will have a tendency to thin out 

 at the top, their lower parts being thicker from the 

 downward gravitation of the particles, and as fresh 

 fluid enters by endosmose, the weakest part will be 

 most stretched. The existence of these conditions 

 in plant-cells will favour their upward growth. 

 Herr Traube succeeded in forming cells of different 

 materials, and imitating many physical processes of 

 growth. The enlargement of the cells in his expe- 

 riments differs materially from the extension of a 

 soap-bubble by blowing more air into it. He 

 observes phenomena of intus-susception aualogous 

 to those of plaut-cells. The enveloping mem- 

 brane of his cells is formed by chemical precipita- 

 tion, which stops when the membrane thickens, 

 and its interstices no longer allow fresh molecules 

 of the membrane-forming material to enter. Eu- 

 dosmose of the surrounding fluid into the cells 



swells them, stretches their membranes, enlarges 

 the interstices, and allows fresh material to enter, 

 and a new layer to be formed. Thus far they 

 imitate living cells. 



Venus's Fly-trap. — At a recent meeting of the 

 Edinburgh Botanical Society Dr. Balfour gave an 

 account of some experiments he had made on the 

 alleged carnivorous habits of Bioncea muscipuht. 

 According to his investigations, the "irritability" 

 of the leaf is resident in six delicate hairs, which 

 are so placed on the leaf that an.insect cannot avoid 

 them iu crawling over it. Chloroform dropped on 

 a hair caused the leaf to close directly, but water 

 has no effect. The contraction lasts for a consider- 

 able time, and only then when an object capable of 

 affording nutriment has been seized. Dr. Balfour 

 therefore considers that the appellation of carni- 

 vorous is fully deserved. 



Maiden-hair Fern (ddiantum CapiUus-Veiiens) t 

 (p. 137). The occurrence of this fern in the Isle of 

 Man at the place mentioned by Mr. H. J. Marsden, 

 is, together with two other localities in the island, 

 duly noted in the Rev. J. G. Cumming's " Guide to 

 the Isle of Man " (1S61), in the chapter headed 

 "Botany." This chapter was abstracted from a 

 paper furnished to the author by the late Prof. E. 

 Forbes, whose knowledge of the Manx flora appears 

 to have equalled iu thoroughness his acquaintance 

 with the fishes and mollusca of the island and its 

 coasts. — Geo. H, HanJciitson. [We collected this 

 fern both at Glen Moy and Peel, in the Isle of Man, 

 more thau ten years ago.--ED. S.-G.'] 



Laburnum.— Yellow and purple racemes grow- 

 ing on same branch. A friend has sent me a branch 

 of laburnum, showing the two distinct colours of 

 flowers ; these have no appearance of having been 

 the result of grafting, as the two kinds are inter- 

 spersed irregularly all over the tree, which is a 

 large one. Is this a common lusus nattirce, and 

 would the seeds produce the same sport ? — L.A.B. 



Insectivorous Plants. — Darwin's new book is 

 now out, and being read by all naturalists. It 

 fairly bristles with facts, and the result is startling 

 to our old-fashioned notions about plants. 



GEOLOGY. 



Cave Animals in Derbyshire.— The Rev. J. M. 

 Mello, F.G.S., is engaged in exploring the crevices 

 and caverns of the Cresswell Crags, on the estate 

 of the Duke of Portland, in Derbyshire. The 

 results up to the present time were submitted to 

 the members in the shape of a valuable and exten- 

 sive collection of animal remains. Among these are 

 the molars of a mammoth {Elephas primigenius) ; 

 the remains, supposed to be almost complete and 



