Septembeb 1, 1891.] 



KNOWLEDGE. 



161 



^C^ AN ILLUSTRATED "^i< 



MAGAZINE OF SCIENCE 



SIMPLY WORDED— EXACTLY DESCRIBED 



LONDON: SKl'TKMJiEB 1, 1891. 



CONTENTS. 



Gnats, Midges, and Mosquitos. — III. By E. A. Butler 

 The Mineralogy of Meteorites. By Vauohan Coknish, 



B.Sc, F.C.S 



Swimming Animals. By R. Lydekkee, B.A.Cantab. 



On the Rhymical Group of Hydrogen Lines visible in 



many Stellar Spectra. l!y A. C. Eanyard 



Notices of Books 



Letters : — H. C Ki'.ssell; A. C. K \xyaed ; W. S. Franks. 

 Some Practical Applications of Electricity. By J. J. 



Stewart 



A Double Planet. By J. E. Gore, F.E.A.S 



Hydroid Zoophytes. By Herdeut Inqall 



The Face of the Sky for September. By Herbert 



Sadler, F.E.A.S 



Chess Column. By C. D. Locock, B.A.Oxon 



PAOK 



161 



103 

 10.5 



las 

 171 

 172 



17-i 

 17.5 

 176 



177 



178 



NOTICE. 



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 Cheques and Postal Orders sliould be made payable to 

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 scriptions, and other business matters should be addressed. 



GNATS, MIDGES AND MOSQUITOS.-III. 



By E. a. Butler. 



IT is difficult for a .stay-at-home Englishman, used 

 only to the minor inconveniences caused by insects 

 in this highly denaturalized country, to conceive the 

 horror with which Gnats and Mosquitos are viewed 

 in tho.sc more primitive regions in which they still 

 exist in incredible multitudes, and to realise the terrible 

 sull'erings they are answerable for ; he is inclined to treat 

 the whole matter almost as a joke, and to laugh at the 

 violence of the execrations which have been heaped on the 

 heads of such insignificant offenders. But there can be no 



question that the plague has been and is still, in many 

 parts of the world, a most real and serious one, and 

 experience shows that the descriptions travellers have 

 given of the numbers of the insects, and the pain and 

 disfigurement caused by their attacks, highly coloured 

 though they often seem, may yet be accepted as having a 

 solid foundation in fact. The exact effect of a Gnat or 

 Mosquito bite, however, upon the human body, varies with 

 the species of insect which produces the wound, with the 

 sensitiveness and temperament of the individual attacked, 

 and with surrounding circumstances. On the borders of 

 the great rivers of the Brazilian forest, where Mosquitos 

 are probably as troublesome as anywhere in the world, the 

 effect is quite different upon Europeans and natives. 

 Accoi'ding to Humboldt, who paid great attention to the 

 subject when he was in the region of the Upper Orinoco, 

 blisters and swelling are not produced upon the skin of the 

 natives, i.e., the copper-coloured Indians, though such 

 results follow in the ease of the white man, new settlers 

 being much more severely dealt with than old residents. 

 Speaking of a white man who had had " his twenty years 

 of Mosquitos," he says, "Every sting leavmg a small 

 darkish-browTi point, his legs were so speckled that it was 

 difficult to recognise the whiteness of his skin through the 

 spots of coagulated blood." That, notwithstanding their 

 immunity from the above secondary effects, the natives still 

 suffer acutely, is manifest from the numerous and energetic 

 devices they adopt to free themselves from the plague, as 

 well as from the extent to which the Mosquitos form a 

 staple subject of conversation. Elevated platforms have 

 been resorted to as retiring places, since the flies are most 

 numerous near the ground, the greater number not rising 

 above 15 or 20 feet; a calico tent suspended from the 

 branches of trees when in the forest, is another device, 

 while indoors there are the well-known nets and curtains. 

 Humboldt speaks of his boatmen as vigorously slapping 

 one another's bare backs to drive away the tormenting 

 insects, and as getting so used to the action that they 

 sometimes slapped themselves in their sleep ; some rubbed 

 the wounds on tlieir comrades' backs with rough bark (!) 

 or again, the women patiently set themselves to pick out 

 from the pustules the drops of coagulated blood. " How 

 are you with regard to the Mosquitos?" was a common 

 form of salutation, while to the native mind, the absence 

 of Mosquitos formed the highest conception of the bliss of 

 heaven. " How comfortable must people be in the moon," 

 said an Indian to his European teacher, " she looks so 

 beautiful and so clear, that she must be free from 

 Mosquitos ! " 



Dr. A. R. Wallace, visiting the same region, says : 

 " Immediately after simset they poured upon us in 

 swarms, so that we found them unbearable, and were 

 obliged to rush into our sleeping-rooms, which we had 

 kept carefully closed. Here we had some respite for a 

 time, but they soon found their way in at the cracks and 

 keyholes, and made us very restless and uncomfortable all 

 the rest of the night." And so far from getting used to 

 them ; " After a few days' residence we found them more 

 tormenting than ever, rendering it quite impossible for us 

 to sit down to read or write after sunset." The people 

 used dried cow-dung burnt at their doors to keep away the 

 insects, and this seemed the most effectual remedy, so 

 that by adopting it, and walking about at the same time, 

 the explorer managed to " pass an hour pretty comfort- 

 ably." Mr. 11. W. Bates, spealdng of Fonte Boa, also i» 

 the same region, says that, "in addition to its other 

 amenities, it lias the reputation throughout the country of 

 being the headquarters of Mosquitos, and it fully deserves 

 the title. They are more annoying in the horns by day 



