HARDWICKE'S SCIENCE-GOSSIP. 



237 



in winter over that in summer be the diminished 

 pressure of the air, which allows a corresponding ex- 

 pansion of fluid in the interior, how thin, as the 

 author remarks, must be the crust of the earth ! He 

 thinks that the temperature of boiling water may 

 perhaps be met with at a less depth than that 

 indicated by the rate of increased temperature in 

 artesian wells, viz, 10,000 feet, but says that modern 

 engineering might possibly be equal to piercing even 

 this depth. His suggestion of sinking a shaft into 

 molten lava is certainly bold, but if things go on as 

 now, the time will come sooner or later, when, as 

 Mr. Gardner says, we shall be driven to try to 

 discover modes of obtaining heat without the 

 combustion of fuel. 



NOTES AND QUERIES. 



Nasturtium. — In reply to L. Lee, permit me to 

 give my view of the laciniated margins (not hairs) at 

 the junction of the blade with the claw of the petals 

 of the so-called nasturtium. For brevity, I will call 

 them bristles, especially as there is a certain rigidity 

 about them. If memory serves me rightly, Kerner 

 mentions them as a contrivance to keep out " un- 

 welcome guests," but does not state in what manner 

 this is brought about, and I fail to see how they can 

 keep out any insects, big or little. The arrangement 

 in the flower of canary-creeper is much the same as 

 in nasturtium, and my remarks to one will apply to 

 the other. Briefly, my view is that these bristles 

 serve the purpose of guiding the visiting insect so 

 as to ensure its coming in contact with the proper 

 organs. This is brought about in the following 

 way : — I. The bristles stand out at a sharp angle to 

 the lamina of the petal. 2. The trifid stigma 

 projects to nearly the same height as the bristles, 

 and midway in the plane between the bristles and 

 the entrance to the spur. 3. The anthers, before 

 dehiscing, lie back between the claws of the three 

 anterior petals and upon the two anterior sepals in 

 nasturtium, but between them in canariensis. In 

 this stage the filaments are bent outwardly at an 

 angle of 45 at least. The anthers advance succes- 

 sively to dehisce in the plane between the bristles 

 and stigmas. 4. The flower is half pendulous. 

 5. Given an insect of proper size and, weight, it will, 

 in making for the spur and guided by the purple 

 blotches and streaks, either clamber over or alight 

 or stand upon the projecting bristles. In any case, 

 the under-surface of the insect will unerringly come 

 in contact with the anthers and stigmas. Bees and 

 wasps are too heavy to do this work properly, and I 

 suppose that these flowers in their native countries 

 have insects especially adapted for their fertilisation. 

 Note length of spur, &c. I do not think the same 

 insect that fertilises the canary-creeper would do for 

 nasturtium. The flowers appear to be proterandrous, 

 but of this I cannot be sure ; if, however, they are, 

 the arrangement for cross -fertilisation is complete. 

 The flowers are wonderfully free from small insects, 

 such as would rifle the nectary without bestowing a 

 corresponding benefit upon the flower ; but what 

 keeps them away I don't know. The plant generally 

 is free from insects, and the leaves retain their 

 intactness to a remarkable degree. In both species 

 of tropaeolum the leaves and stem are glabrous, and 

 I am inclined to think that their principal protection 



is their pungent taste and smell. — J. Hamson t 

 Bedford. 



Pied Fly - Catcher ; Woodcock ; Wood - 

 Warbler. — Notes in the last two or three numbers 

 of ;Science-Gossip show that the pied fly-catcher is 

 extending its range. It has not been recorded from 

 the south-west of Scotland, but last year a pair made 

 their appearance, about May 13, in a glen containing 

 a considerable number of old alder-trees, which form 

 a favourite nesting-ground for tits, redstarts, and 

 spotted fly-catchers. On May 31 the pied fly- 

 catchers' nest, which was placed in rather a deep hole 

 in one of the alders, and composed entirely of grass 

 — coarse grass outside, and Tery fine grass inside — 

 contained six eggs, rather paler than the redstarts. 

 One egg was taken for a specimen, four were hatched, 

 and one was left in the nest, which contained a half- 

 formed bird. This year the fly-catchers occupied the 

 same nest, and laid only three eggs ; but none of their 

 young seem to have returned to the district of their 

 nativity. Two other birds seem to be extending 

 their breed-range — the woodcock and wood-warbler. 

 The woodcock breeds plentifully in the highlands of 

 Scotland — at least, in some parts of them ; but it is 

 more frequently met with during the breeding season 

 in Dumfriesshire now than it was a few years ago. 

 The wood-warbler has increased immensely during 

 recent years. Ornithologists of Macgillivray's time 

 seem to have considered it rare in Scotland, whereas 

 now it is almost as plentiful as the willow wren, and 

 is to be heard in every bit of wood in the district. 

 On landing from a steamer at Balmacarra, about 

 four A.M. on a June morning in 1883, it was the first 

 bird I heard, and it was almost constantly heard 

 along the wooded banks of the Caledonian Canal, 

 from Inverness southward. — Scot. 



The Common* Sunflower. — That the bracts are 

 modified leaves is not a matter of doubt. It is not so 

 clear that the ray-floret is derived from a bract. Most 

 botanists believe the series of bracts to be continued 

 in the scales which may be found at the base of all 

 the florets, and surrounding each blossom in such a 

 way that Mr. E. A. Swan calls it a rudimentary 

 calyx. As described in most works of elementary 

 botany, every floret of the sunflower, or other plant of 

 the same natural order, is a flower with organs 

 corresponding to similar organs in other flowers, 

 which appear in the axils of leaves, as in the fuchsia, 

 or of bracts, as in mignonette. Perhaps the analogy 

 may be best made out in the head of a teasel, in which 

 the bracts at the base of the flowers bear more 

 resemblance to those of the sunflower, but are larger. 

 In the teasel, too, the parts of the flower are more 

 easily distinguishable. The real calyx of the sun- 

 flower appears in what E. A. Swan calls a short 

 pointed wing from either side of the achene. These 

 wings are analogous to the sepals forming the calyx 

 of a proper flower, and, in the language of botanists, 

 are sepals as much as those which cover the unopened 

 blossom of a poppy ; the corolla consists of five 

 coherent petals, which, in a ray-floret, are expanded 

 into a flat limb, instead of being tubular. The 

 stamens are held by modern botanists to be modified 

 leaves, of which the leaf-stalk is represented by the 

 filament, and the blade by the anther. — John Gibbs. 



Nests within Nests. — During a recent visit to 

 Ashdown Forest, while looking for young squirrels, 

 I found no less than four old dreys which were 

 tenanted by the common, yellow-banded humble- 

 bee {Bombus terrestris) ; and in one case the bees had 

 not been the first to take possession of the deserted 



