280 



HARDWICKE'S SCIENCE-GOSSIP. 



meat, the parrot whistled in harmony with the tune, 

 and then apparently knowing that it was time for 

 supper, immediately began its " Ask for it ;" and once 

 at family worship while only one voice was speaking 

 Polly suddenly called out "stop, short ! " which good 

 advice perhaps I had better follow. — William Budden, 

 Ipswich. 



Sheet Lightning is supposed to be produced in 

 the cloud itself illuminating the whole mass, and to 

 be formed of brush discharges between clouds, 

 while zigzag lightning is a true electrical discharge 

 between the clouds and the earth. Brush discharges, 

 analogous to sheet lightning, may be seen on the 

 projecting parts of the conductors of a machine 

 worked in the dark. The reason that ' ' fork lightning " 

 takes a zigzag direction is supposed to be due to 

 the increasing resistance of the atmosphere as the 

 spark proceeds, so that having got to one point of its 

 course, the resistance is so great that it follows the 

 path of least resistance, which is a path lying to one 

 side of its previous course. — Walter G. Woollcombe. 



Sheet Lightning. — The common explanation of 

 sheet lightning, that it is the reflection of forked 

 lightning, has misled C. B. by his naturally suppos- 

 ing the word reflection to mean reflection as in a 

 mirror. This term reflection is a misnomer. The 

 generally received theory of sheet lightning is that it 

 is the illumination of the clouds, &c, by a rapid, a 

 vivid flash of forked lightning which has not acted 

 strongly enough upon our retinas to produce a visible 

 image of the fork ; so that, the only intimation we 

 receive of the flash is the image on our retinas of the 

 momentarily illuminated cloudscape. — Edward B. 

 Parfitt. 



Dragon-fly. — The description given by your 

 correspondent J. A. Wheldon of the dragon-fly he 

 caught is very indefinite, and is hardly sufficient to 

 enable one to identify the species. It may perhaps 

 belong to the genus of slender-bodied dragon-flies 

 Agrion. In A. minium, for example, the predomi- 

 nating colour is a beautiful vermilion-red, but on 

 the thorax are conspicuous streaks of yellow ; the 

 "stigma" (or the thickened portion of that strong 

 nervine which runs along the upper part of the wing) 

 is in both pairs clearly rhomboidal in shape. — 

 C. Brands Young. 



Dragon-flies. — Since capturing the dragon-fly 

 mentioned in the last Science-Gossif, I have seen 

 several more like it. They appear to be pretty 

 numerous here, which goes a considerable way to 

 disprove the supposition of H. E. Watney, that 

 they have been accidentally introduced. I saw 

 several pairs in cop. but am uncertain as to whether 

 both, or only one were possessed of a scarlet coat. 

 The body of the one I caught has since faded, but 

 the spots in the corners of the wings are as bright 

 as ever. I intend restoring the colour of the body 

 with paint. — J. A. Wheldon. 



Preservation of Fungi. — I should feel very 

 much obliged if any of your correspondents could 

 inform me of any good plan of drying, or otherwise 

 preserving fungi for the herbarium. Is it possible 

 to dry such species as Agaricus procerus, Coprinus 

 comatus, &c, so as to make decent and recognisable 

 herbarium specimens ? — J. A. Wheldon. 



Spider-killing Wasps. —I was very much in- 

 terested with the letter on South African "spider- 

 killing wasps " which appeared in the September 

 number of Science-Gossip. At Heidelberg this 



year, I saw a hymenopterous insect dragging a dead 

 or stupefied spider along a bank in one of the 

 woods, but unfortunately I frightened it away, so I 

 could neither observe what it was going to do nor 

 preserve it for future identification. From the 

 situation, however, I think its nest would be sub- 

 terranean. Can you, or any of your readers, give me 

 the name of the European or African or any other 

 hymenopterous insect-killing spiders ? A great many 

 predacious Hymenoptera were observed by M. Fabre 

 at Orange (near Avignon), and are described by him 

 in a most charming little book called " Souvenirs 

 Entomologiques " (Paris, Librairie Delagrave, 15 Rue 

 Soufflot, 1879, price not more than four francs), a 

 book which has received a good deal of notice among 

 foreign entomologists. But no spider-killing Hymen- 

 optera are mentioned in this work, although the 

 habits of two species of Cerceris and three of Sphex 

 are described minutely. These insects in paralysing 

 their prey act as if they had a perfect knowledge of 

 their anatomy, they insert their stings into the centres 

 of the nervous systems of their prey in a most 

 scientific manner. The Cerceris kills beetles in which 

 the nervous centres are collected nearly at one point 

 and stings them once ; for a similar reason, one kind 

 of Sphex stings grasshoppers three times. And yet 

 we cannot believe these Hymenoptera know why 

 they do so, as the Sphex will, if its grasshoppers 

 are removed from the nest, cover it up as carefully 

 as if it contained grasshoppers and eggs, although 

 doing so is perfectly useless. Such cleverness on 

 one hand and stupidity on the other prevent our 

 attributing these acts to reason, it must be instinct. 

 With other Hymenoptera M. Fabre has proved it to 

 be the same. Observe them under ordinary circum- 

 stances and you will be astounded at their wisdom. 

 Observe them under artificial conditions, and they 

 will go through the same routine as before, although 

 it may be highly inconvenient. They have learnt the 

 part they must play in the world by heart, and can 

 only go through it in one way ! The Bembex fear- 

 lessly attacks and kills large Tabanida;, and yet it is 

 terrified by a little dipterous insect which it could 

 at once destroy. The latter lays its eggs on the 

 food the Bembex is taking to its larva, and the larva, 

 of this intruder eats the food of the Bembex larva 

 leaving the latter to starve. The wasp mentioned 

 by your correspondent as capturing caterpillars is 

 probably a species of Ammophila or sand wasp, and 

 her observations agree exactly with those of M. Fabre. 

 This subject is a very interesting one, and further 

 observations would no doubt reveal many new and 

 curious facts.— G. H. Bryan. 



Preserving Crustacea. — I have set up several 

 small crabs and other crustaceans, after the manner 

 described by Mr. Lovett in the April number of 

 Science-Gossip, and find to answer excellently. 

 One operation, not mentioned by him, I find very 

 advantageous, viz. a wash of corrosive sublimate and 

 spirits of wine, applied internally and outside. — J. A. 

 Wheldon. 



Scarcity of Bee Orchis, &c. — I can quite bear 

 out J. S.'s experience with Ophrys apijera this season. 

 I had promised to procure a friend living specimens, 

 having no doubt of my ability to obtain them, but 

 though, with other friends, I made a careful search 

 in the former habitat of the plant and found chlora 

 as usual, we could not see a specimen of its com- 

 panion. I should be glad to hear other corre- 

 spondents' experience, and to know to what causes 

 they consider the scarcity of the plant may be 

 referred. — R. B. Towndrow. 



