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HARDWICKE'S SCIEN CE- GO S S IP. 



Cleaning Diatoms. — I skall_ be very greatly 

 obliged if you will favour me witb a word of in- 

 structiou as to the cleansing of diatoms. In com- 

 mon with several friends beginning the study, I 

 have been attempting the preparation of diatoms, 

 both fossil and otherwise. We are all in the same 

 difficulty, and it still remains, after using all the 

 processes described in Mr. Davis's book of instruc- 

 tions. After boilings in sulphuric, hydrochloric, 

 and nitric acids, and following every direction given, 

 our diatoms are still mixed with a kind of ftocculeut 

 matter of which we cannot get rid. Water washings 

 and separations of every kind we can devise are all 

 of no avail. — W. Winsford. 



Death's-Head Moth. — I have several times had 

 the larvse of the Death's-Head Moth brought to 

 me. Last year, as I had previously done, I put a 

 larva of the above in the garden, under a glass 

 cover, with some potato-leaves. In two or three 

 days it buried itself. After waiting about a fort- 

 night, I took the pupa out of the ground ; and as I 

 held it in my hand, between my forefinger and 

 thumb, it made the same shrill, squeaking noise as 

 I have heard the perfect insect make. The sound it 

 made was similar, but much fainter. — W, F. Foottit, 

 Newark, Notts. 



Death's-Head Larvae.— I expected to see in 

 your last month's issue of Science-Gossip an 

 answer from some of our leading entomologists to 

 the remarks of your correspondent as to the power 

 which the pupse of A. atropos have to produce noise. 

 The only authority which he mentions for this fact 

 is Newman, but it has been recorded by many 

 others, amongst which are De Geer, Euessly, 

 Reaumur, Kirby, Spence, &e., some of whom your 

 correspondent will do well to consult before express- 

 ing his doubts on the subject. Having myself 

 heard this noise, I trust a short account of my own 

 observations may not be uninteresting to your 

 readers. Last season I had a large number of the 

 above species dug up, amongst which was a very 

 large and fine _ specimen, which, however, was 

 unfortunately injured, having a small crack in the 

 cephalotheca or head-case, although so small that 

 but little matter exuded from it. Thinking that I 

 might save it, I tied some lint carefully over the 

 crack, and in a day or two the injured part was 

 quite healed. The other pupae were removed to the 

 breeding-cage, and being buried 1 had of course no 

 chance of hearing whether they made a noise or 

 not, but the one that had been injured I kept in a 

 little damp moss, for the purpose of seeing if it 

 would recover. In this position it was kept for 

 about two months, during which time I repeatedly 

 heard the noise which your correspondent doubted. 

 On being touched it would emit a noise resembling 

 the chirrup of a grasshopper. After remaining in 

 this state for the time before mentioned, it gave 

 up the ghost, much to my disappointment. The 

 means by which this noise is made is simply by the 

 pupae ebngating and contracting their cases, the 

 noise being produced by the sudden snap of the 

 rings resuming their original position after the 

 contraction. — A. Mercer. 



The Death's -Head Moth {Acherontia atropos). 

 — I have during my entomological experience had 

 dozens of larvse— of all sizes— of this interesting and 

 peculiar species. I quite agree with Mr. Newman 

 and other authors that in three stages of its 

 metamorphosis it has the power of producing a noise. 



The larva turns its head from side to side with great 

 quickness, as if by a spring, when disturbed, and 

 during this contortion I have frequently heard a sort 

 of snapping noise ; however I have observed that 

 some larvse never make the noise, and others only 

 occasionally, though all have the twisting motion of 

 the head ; so the sound must be a voluntary pecu- 

 liarity of the larva. I have once or twice heard the 

 pupa squeak, but in each case a moth was pro- 

 duced from the squeaking pupa in a few hours 

 after. Before the moth emerges, the pupa will often 

 appear upon the surface of the ground, caused I 

 suppose by the movements of the enclosed imago. — 

 G. B. C, Ringwood. 



Pupa op Deatk's-Head Moth producing 

 Sound— I see in your pages a discussion as to the 

 ability of the pupa of Acherontia atropos (Death's- 

 Head Moth) to produce sound. One season I had 

 a very large quantity of these pupse ; they were laid 

 on the surface of soil in a box, and covered witb 

 damp moss; they were kept in the corner of a warm 

 room to facilitate the exit of the imago. Many a 

 time did the pupse " squeak," although more faintly 

 than does the perfect insect, and it was noticeable 

 that this usually occurred shortly prior to the ap- 

 pearance of a moth. On first hearing these sounds 

 we concluded that an imago had emerged; not, how- 

 ever, finding any on the sides of the box, we sought 

 among the moss, but without success. After a few 

 such occurrences, we became aware that the sound 

 preceded an exit of a perfect insect. It was a usual 

 remark, when the sound was heard by those in the 

 room, that "another moth will soon be out." Of 

 course no one now doubts the ability of the imago 

 to produce sound ; we could at any time elicit the 

 " squeak " by giving the moth a poke, or by other- 

 wise annoying it. — George Gascoyne, Newark. 



Death's-Head Moth. — Some correspondents in 

 your last number expressed a doubt as to whether 

 the larva and pupa make any noise. I cannot 

 answer for the latter, but I have frequently heard a 

 sound from the caterpillar. It was generally short 

 and abrupt, like the tick of a watch, but sometimes 

 more prolonged. I could always induce the creature 

 to make the noise by touching it rather smartly 

 with my finger about the middle. It nearly always 

 turned its head round at the moment the souud 

 escaped. The noise made by the imago is much 

 longer and shriller, and might really sometimes be 

 called a " shriek." — Henry Ullyett, Folkestone. 



Preserving Objects.— Can any of your readers 

 give me a recipe for preserving insects ? I want to 

 keep them from summer until winter in some way 

 that will keep them moist (and not injure them), so 

 that they may be dissected and mounted for the 

 microscope as if fresh killed. I have tried spirit, 

 spirit and water, and also turpentine, but without 

 much success. The spirit seems to do best, but it in- 

 jures some insects very much. If the object is dried, I 

 cannot succeed in softening it, so as to make it like 

 a fresh-killed one. I should not trouble you, but I 

 cannot get this information, and I am sure many of 

 your readers must have felt the want of some ready 

 way of disposing of newly-caught insects when time 

 will not allow of their being dissected at once. — 

 C. L. J. 



Preserving Spiders. — Can you or any of your 

 correspondents tell me the best way of preserving 

 spiders, so as to keep them from shrivelling up, 

 and retain their markings ? — B. IV. S. 



