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HARDWICKE'S SCIENCE-GOSSIP. 



pass. The fluctuations of current are especially 

 unpleasant in machines where the dynamo-electric 

 principle is thoroughly adopted, i.e. where the coils 

 of armatures and coils of magnets together form only 

 one circuit. Every increase of resistance in the 

 circuit here will cause diminution of current, as a 

 matter of course ; in the dynamo-electric machine, 

 when the current is weakened, the electro-magnets 

 are also weakened. Let us suppose, for the sake of 

 illustration, that the current has to feed an arc lamp, 

 and suddenly a piece of one of the carbons springs 

 off, thereby increasing the resistance. The current 

 will decrease, and the machine will furnish a weaker 

 current just at that particular moment when a 

 stronger current is required to maintain the lamp 

 burning. Although the lamp might not go out, a 

 change in the intensity of the light will certainly be 

 produced. As we have already seen, it was for this 

 reason that Wheatstone placed the electro-magnets in 

 shunt, so that the circuit of the magnets should be 

 separated from that of the armature and receiver. 

 Brush makes the outer circuit independent of the 

 intensity of the magnetic field by providing the 

 electro-magnets with coils of much thinner wire in 

 addition to the ordinary coils, the ends of which are 

 connected with the collecting brushes. Marcel 

 Duprez obtains current regulation along with the 

 distribution, and aims at securing (i) that each 

 portion of the apparatus shall receive the necessary 

 current, and shall act independently of the others ; 

 (2) that the necessary regulation shall be executed by 

 the machine itself; (3) that this regulation shall be of 

 such a kind that the machine produces only such 

 current as is required for the apparatus inserted in the 

 circuit. — From "Electricity in the Service of Man." 



Cuckoo and Magpie. — We have in our garden 

 here, now, a most curious spectacle : a young cuckoo 

 being reared by a pied wagtail. The poor little bird 

 can scarcely satisfy the adopted one with food, though 

 it supplies a fly about every minute. Is not this 

 strange. I thought the hedge-sparrow was generally 

 selected as a foster-parent? — J. A. Smith. 



Fasciation. — A curious case of " fasciation " 

 came under my notice recently in a garden ten miles 

 from here. A common vegetable marrow threw out 

 a branch about fifteen feet long, forked about three 

 feet from the growing end. This branch widened as 

 it grew, measuring from three to four inches across 

 near the fork, each limb being as wide as the branch 

 a little below the fork. Near the fork were growing 

 eight marrows, all large enough to cut, their stalks 

 all starting from a line running nearly straight across 

 the branch. Near the end of the larger limb of the 

 fork was another row of marrows, all about one and a 

 half inch long, but their growth, as well as that of 

 the rest of the branch, which bore many small leaves, 

 appeared to be arrested by the rapid development of 

 the marrows lower down. A well fasciated branch of 

 willow was brought to me last autumn ; the twigs are 

 parallel for some eighteen inches, then diverge for 

 five or six inches more. 



Packing Ripe Fruit. — Can any correspondent 

 give a scientific reason for the practice of packing 

 ripe fruit (plums, apples, etc.) in fresh stinging- 

 nettle leaves ? The practice seems to prevail both in 

 this neighbourhood and in East Kent, but I never 

 heard of it till lately. I have seen baskets of fruit for 

 market covered with nettles, and I know if fruit for a 

 country show — apples — gathered a few days before- 

 hand, and laid in nettle leaves, often changed, the 

 reason given in both cases being that the nettles 



restored the bloom destroyed by handling, or 

 increased its quantity. The plan seems so curious 

 that further information would, I think, be interest- 

 ing. The apples were undoubtedly improved by the 

 process, but I cannot see the connection between 

 cause and effect. — M. E, Pope. 



Do Ants Hear? — I see some little discussion has 

 been taking place in your magazine about the hearing 

 of ants. Mr. Whalmore thinks they do not hear, and 

 Mr. Bowman believes that they do hear. I do not 

 think there exists any question at all, for if I may be 

 allowed a word, I may say that auditory organs have 

 been demonstrated in all the Insecta except the 

 Thysanoptera. Indeed, the sense of hearing is so 

 keen in insects, that there are as many as two 

 hundred auditory organs in some species situated on 

 the dorsal aspect of the abdomen, antennae, palpi, 

 legs, and even on the wing-membrane. Each organ 

 is generally known as a chordotonal organ. Their 

 essential structure is the presence of a nerve ending 

 in a ganglion, which in its turn ends in end-organs 

 which are connected directly or indirectly to the 

 hypodermis of the integument. Each end-organ 

 consists of an " endstift" or terminal rod enclosed in 

 a scolopophore or sheath. If Mr. Whatmore is still 

 in doubt, he will be satisfied by turning up to 

 pp. 502-503 of the recent edition of Rolleston's 

 " Forms of Animal Life," (Clarendon Press, 1888). — 

 y. W. Williams. | 



The Metamorphosis of the May Fly. — I 

 picked up a common May fly {Ephemera danica) from 

 off a grass stalk at Olney, and placed it beneath a 

 tumbler, when to my astonishment, it commenced to 

 pull its wings out of their skins as though they had 

 been kid gloves. Caterpillars increase in bulk by 

 this process, but it is strange to observe an insect 

 already perfect, so behaving. I am told that there is 

 an allusion to this feat in the Water Babies. — 

 A. H. Sivinton, I Ttidor Villas, Gery Street, Bedford. 



Aphis Fluid.— W. E. G., Bristol, will find it 

 stated on page 88, vol. 2, Kirby and Spence's 

 Entomology (ed. 1817) that the aphis fluid "issues 

 in limpid drops from the abdomen of these insects, 

 not only by the ordinary passage, but also by two 

 setiform tubes placed one on each side just above it." 

 Again, in an extract from Stuart's " Elements of 

 Natural History "- quoted in Wood's " Linnrean 

 Genera of Insects" (ed. 1821), the fluid is stated 

 to exude "partly from the horns on their abdomen, 

 and partly from two orifices at the same place." In 

 the Micrographic Diet. (ed. 1S83), page 62, it is 

 stated, that " Kaltenbach considers the abdominal 

 tubes to be merely produced stigmata, and states that 

 the saccharine fluid is emitted through the anus," and 

 that "this is also the opinion of De Geer, Kyber, 

 and others" — F. Wain Sampson. 



Land Shells near Norwich. — It may be of 

 interest to Norwich conchologists and others to know 

 that I have recently found Helix aculeata and If. 

 pygmcEa in this locality, IP. aculeata in plenty in a 

 lane adjoining the western suburbs of the city, and 

 // pygmcea at Hellesdon, near Norwich, and a few 

 other places close by. I do not think that these 

 species have hitherto been recorded as living in this 

 district. — Arthur May field. 



Two Replies. — In reply to W. P. H's query, 

 appearing under the heading *' Animalcula," in the 

 " Notes and Queries" column of October's issue of 

 this journal, I confess me much guilty, but, at the 

 same time, may I venture to suggest that people who 



