April 20, 1S99] 



NA TURE 



583 



that we have chiefly to rely for its specific characters, especially 

 valuable features being often furnished by the banding of the legs 

 (and palpi also in some species ni Anopheles), any method of 

 collecting, preserving, and sending home specimens that does 

 not takejaccount of these points is likely to be of little use. 



In November last year, by desire of Prof. Ray Lankester, the 

 writer drew up a series of instructions for the collecting of 

 mosquitoes, which were forthwith printed by the British 

 Museum in pamphlet form, under the title " How to Collect 

 Mosquitoes." Copies of this pamphlet have been forwarded by 

 the Museum to possible helpers in all parts of the globe ; while 

 the Colonial Oflice, which is taking a great interest in the 

 matter, has furnished other copies (accompanied by injunctions 

 to collect) to the medical officers under its control throughout 

 the empire. It is hoped that ere long, in response to these pre- 

 liminary measures, consignments of properly collected mosquitoes 

 •will commence to flow steadily into the British Museum. 



The pamphlet of instructions contains a list of the articles 

 required, and adetailed statement of the proper method of collect- 

 ing, killing, and preserving mosquitoes intended for determin- 

 ation. The most important points in the technique of mosquito- 

 collecting are that the insects, when captured in the open, must 

 be brought home alive in pill-bo.ves of a special kind, must on 

 no account be put into spirit, but be killed by being placed for a 

 few moments in a cyanide bottle, and then immediately pinned 

 on an exceedingly fine pin (known to English entomologists as 

 a "No. 20"), which, in order to protect the insect's legs, is 

 thrust through a disc of card, the latter being finally supported 

 by being transfixed by, and drawn rather more than half-way 

 up, an ordinary or toilet pin. The pamphlet concludes with 

 ■directions for the transmission to England of specimens intended 

 for the British Museum. It may be added that copies of the 

 pamphlet can always be obtained on application to the Director, 

 the British Museum (Natural History), Cromwell Road, London, 

 S.W. ; while, if further information on any point is desired, I 

 5hall be happy to supply it myself. 



Unfortunately, widely as the pamphlet has been circulated, it 

 has not yet reached the hands of all mosquito-collectors ; and I, 

 therefore, avail myself of the present means of making its 

 •existence more extensively known, the impulse to do so having 

 been supplied by certain recent arrivals. From the nature of 

 the present movement very many collectors — perhaps the 

 majority — are -medical men who, unfortunately, seem endowed 

 with a sort of natural instinct prompting them to preserve every- 

 thing by placing it in a bottle of spirit or glycerine. Mosquitoes 

 when treated in this manner reach England in sorry plight. 

 Sundry bottles of specimens from the West Indies and the Far 

 East are now before me. The latter are in the worse condition ; 

 continual shaking in the course of the long journey home has 

 precipitated most of the legs to the bottom, which is quite 

 covered with them. Since all previous descriptions of mos- 

 quitoes, as indeed of all other Diptera, have been prepared from 

 dried specimens, a mosquito "preserved" in this fashion must 

 be removed and dried before any comparison can be made of it. 

 Such a specimen, with its scales either washed away or matted, 

 and its body shrunken and shrivelled, is a bedraggled-object 

 indeed. There may, perhaps, to some people, be a peculiar 

 appropriateness in the idea that the last state of the sharp- 

 tongued mosquito should be similar to that of a victim of the old- 

 time ducking-stool, but the .scientific value of the specimen so 

 treated is little greater than if it had been crushed with the 

 hand. 



A bottle of mosquitoes in spirit from one West Indian locality 

 is not only thick with floatmg scales and fragments of legs and 

 wings, but is also distinguished by a turbidity unpleasantly 

 suggestive of putrefaction. 



Another method recently adopted is to dry the mosquitoes 

 and send them home in small tubes containing cotton-wool ; 

 the results are nearly or quite as disastrous as when glycerine 

 or spirit is used. It seems to be forgotten that because speci- 

 mens may be practically perfect when put into a tube, it by 

 no means follows that they will reach London in the same con- 

 dition. Mosquito legs adhere to cotton wool, and inevitably 

 get pulled off in numbers ; while if any space is left between the 

 specimens and the wool, the former by dint of constant shaking 

 become reduced to a sort of coarsely granulated powder. This 

 is the actual condition of two tubes of specimens recently 

 received. As an instance of misdirected energy it may be worth 

 while to quote one collector's description of this method ; he 

 writes as follows : — 



NO. 1538, VOL. 59] 



" I am making a collection for you of all the dififerent mos- 

 quitoes that occur here ; they are put into a tube after having 

 been killed in the cyanide bottle, a bit of cotton wool pressed 

 against them, and then kept in the exsiccator over anhydrous 

 chloride of calcium — this to free them of moisture, and thus 

 prevent mould ; afterwards corked up. 



" Upon arrival remove cork and allow the tube to remain a 

 day in a damp chamber ; this can be easily made by inverting a 

 tumbler over a piece of wet blotting-paper ; the insects will 

 absorb some moisture, and can afterwards be handled without 

 being broken, mounted on cards or otherwise set up." 



Now, when it is absolutely impossible to pin specimens, 

 according to the method prescribed in " How to Collect Mos- 

 quitoes," there is just a chance that they may reach London in 

 a more or less useful condition if treated as described in the 

 foregoing extract, provided that a plug of thin tissue-paper is 

 substituted for the cotton-wool ; this plug should be pressed 

 down until it is in close contact with the specimens, while the 

 latter are still soft ; the tubes should be as narrow as possible — 

 preferably not more than ^ inch in diameter, and must of course 

 be tightly corked ; they should be packed in a tin box filled 

 with cotton wool, so as to reduce all shaking to a minimum. 



I would, however, strongly urge no one to adopt this method 

 who can obtain the articles necessary for pinning specimens in 

 the manner prescribed in the pamphlet of instructions, since 

 the latter is the only really satisfactory plan. Specimens 

 thrown into spirit are absolutely useless ; masses of material 

 entangled in cotton are nearly as bad. It is a pity that so much 

 well-intentioned labour should be thrown away. 



Ernest E. Austen. 



British Museum (Natural History), 



Cromwell Road, London, S.W., April 14. 



Sunspots and Rainfall. 



The question of sunspots and air-temperature was recently 

 considered in these columns with the aid of a method in which 

 each month since 1841 (at Greenwich) was first characterised as 

 -f or - , according as the temperature was above or below the 

 normal ; a year with more than the average number of plus 

 months being considered war/n, and with less, cold. 



Rainfall data may of course be treated similarly, and your 

 readers may perhaps be interested to see how the method works 

 out in this case. The values are those for Greenwich, extending 

 as far back as 1S15 ; but those previous to 1 841 are to be 

 thought less trustworthy.than the others. Two sets of averages 

 have been employed for the two periods (before and after 1841). 



Taking 5-4 as the average number of wet months in a year 

 for the whole period, and so 27 as the average number iri 5 

 years, let us now consider the five-year groups about maximum 

 and minimum sunspot years, noting how the number of wet 

 months in each of these groups differs from the average. 



Difference 



Sum. ... -I- i8 



A pretty distinct contrast appears in these two tables.' There 

 seems to be (at Greenwich) a greater tendency to wetness in 

 years about sunspot miiti/na, than about maxima. Thus in seven 

 maximum groups we find only one (e) with an excess of wet 

 months ; while in the seven minimum groups an excess appears 

 to be the rule, to which there are two exceptions (marked e). 



1 A still better contrast, I think, comes '^",',P" comparing the five years 

 ending with : * * 



