BLOODSUCKING INSECTS AND TROPICAL DISEASES. 179 



however, be diminished by pinning in a corner of the box a small piece of sponge 

 saturated with the strongest carbolic acid, which should be constantly renewed. 

 The greatest care must be taken to prevent specimens getting loose and rolling 

 about in transit, since in this way a single loose disc might easily do irrepar- 

 able injury to many other specimens in the box. To prevent this the pins 

 supporting the discs should be inserted as tightly as possible into the cork- 

 carpet or pith, and they should all be driven in to the same level, after 

 which a sheet of soft paper (newspaper does very well) can he fixed into the 

 box, resting on the heads of the supporting pins, in order to minimise the 

 damage should a disc happen to get loose. The box containing the specimens 

 should be well wrapped in cotton-wool or similar material, to secure it from 

 shocks on the journey, and firmly packed in an outer case for transmission (by 

 parcel-post if possible and if the package is not too large) to England. 



Number of Specimens of each Species required. 



At least half a dozen specimens of each sex of a species should, if possible, 

 always be obtained, and a good look-out should be kept for specimens showing 

 any abnormality in structure, coloration, or sue. When the collector remains 

 long enough in one spot, he should always endeavour to obtain specimens of a 

 species on different dates, in such a way as to throw as much light as possible 

 on the duration of its seasonal occurrence. Similarly the attempt should be 

 made to illustrate the geographical range or local distribution of a species, by 

 collecting specimens in as many different localities as possible. Specimens of 

 species taken in new localities, though common elsewhere, will always be 

 valuable. 



In addition to Pinned Specimens, others should be 

 Preserved in Alcohol. 



Pinned specimens should always, if possible, be accompanied by others pre- 

 served in alcohol. The following directions have kindly been supplied by 



Lieut.-Colonel Gr. M. Giles, who has found that the method indicated answers 

 well in practice : — " Flies intended for anatomical examination must be fixed 

 by heat, since their chitinous envelope is penetrated so slowly by alcohol that, 



f this be not done, they decompose before the preservative can reach them. It 

 is sufficient to bring them to boiling temperature in a test-tube of water, but for 

 delicate histological work it is better to boil in a mixture of equal parts of 90 

 per cent, alcohol (ordinary rectified spirit) and aqueous solution of perchloride of 

 mercury, 1 in 500. Even protozoal parasites are well preserved by this method. 

 When fixed, preserve in 90 per cent, alcohol. Methylated spirit should not be used, 

 since its acidity and other impurities may lead to embarrassment in the use of 

 aniline stains/' The specimens should be preserved in small glass tubes, with 

 a plug of soft paper placed inside on the top of the specimens to prevent them 

 from being injured by washing about in transit. A slip of paper, on which 

 all necessary data should be written clearly in pencil, should be placed inside 

 each tub 3, and tho pinned spaciraens of the same species should be labelled with 



