16 



HARDWICKE'S SCIENCE-GOSSIP. 



^vith the exception of an alternate stretching and 

 contracting of its legs, as thougli trying their 

 strength before the next move. 



When sufficiently strong to bear the wti-htof 

 the body, it gently turned itself backwards and laid 

 hold on the head of the pupa-case. As soon as it 

 was firmly fixed on if, the remainder of the abdo- 

 n;en dropped out of the case and hung outside it. 

 I!p to this time tlie wings had not begun to unfold; 

 but as soon as the body was fixed and lengthened, 

 theu commenced the unfolding of the wings, pre- 

 senting a very beautiful sight (especially if viewed 

 tlirough a pocket lens). The body was curved in 

 such a way that the wings should not come in con- 

 tact with it : at that time they were iu so soft a state 

 that to touch anything would injure their delicate 



tissues. 



The creature appeared fully aware of tbis, as shown 

 by its placing itself exactly in a position where none 

 of the surrounding objects could touch it. The 

 wings unfolded downwards, close together, quite 

 soft, but when sufficiently dry and hardened, tliey 

 gradually expanded, and showed by a quivering 

 motion that they were ready for flight. Their un- 

 folding perfectly took about twenty-five minutes. 



I have had four pupa; come out of one aquarium 

 at different times, but up the same stem of the plant. 

 It is interesting to see each of them place itself iu 

 the same position as its predecessors, and go through 

 the movements, as though it had been the same in- 

 sect performing over again. 



My attention was drawn to four white thread-like 

 filaments left attached to the empty and deserted 

 pupa-case, two of which are fixed on the middle of 

 the upper part of the thorax ; their length drawn 

 out of the corresponding part of the emerging insect. 

 The other two were fixed one on cacli side, about a 

 quarter of an inch farther down, below where the 

 wing-cases open from the thorax. On placing them 

 under the microscope, I found them to be tracheae, 

 and on further examining the empty case the trachea 

 could easily be traced down each side to the breath- 

 ing apparatus or spiracles at liie tail. As the per- 

 fect insect will breathe by other spiracles, differently 

 situated, this set of tracheae is rendered useless and 

 is withdrawn from the insect at its transformation. 

 The opening out of which they are drawn is closed, 

 so that they cannot be detected, as far as my ob- 

 servation went. 



1 have one pupa living, and shall wateli it through 

 the winter, as it is not likely to come out, now it is 

 so late. I fed it at times with flies by placing them 

 on a fine wire and gently moving it before the pupa's 

 head. Tlie latter quickly threw out its curiously- 

 formed mask, seized ir, and conveyed it to its 

 mouth. 



They are very voracious, and will feed on almost, 

 any aquatic insects ; as shrimps, beetles, small min- 

 nows, &c. I iiave sometimes given it a quantity of 



the Baphuea Fidex, when a good opportunity was 

 aiforded to witness the repeated movements of the 

 mask, in catching and conveying them to its mouth, 

 when its formidable jaws soon dispatch them. The 

 jaws and mask make good subjects for the micro- 

 scope, with a low power, 



Canterbunj. James Eullagee. 



MICEOSCOPY. 



Pekhaps some of your correspondents could 

 inform me whether the "test-scale" Poduracanuow 

 be anywhere found . Every microscopist is familiar 

 wi:h tlie common species of Tjepidocyrtns curvicollis, 

 which supplies scales of the same general character, 

 but by no means either so beautiful or so useful as 

 tests. My own experience would incline me to 

 think that the test-scale insect must be a distinct 

 species, and not a variety of Lepidocyrtus. 1 have 

 collected and examined great numbers of specimens 

 from localities widely distant ; but tbougb some of 

 these were passably clear in their markings, yet. 

 when compared witb the other in the microscope, 

 the dilfercuce was instantly evident. They differ, 

 iu fact, as much as either differs, e.g., from Tern- 

 plctoida. The professional preparers, I find, can 

 supply nothing except the commou kind. I have 

 heard it said, indeed, that the scale in question ma.y 

 be got from a bronze-coloured insect ; but this is 

 in direct contradiction to Mr. U. Beck's statement 

 in his work on the microscope, iu which he says 

 that his scale is got from an insect of a dark lead- 

 colour, and about -^ of au inch long (p. 145), Mr. 

 M'lntyre is, I presume, better informed on this 

 subject than any one. else; yet L have looked in 

 vain among his communications for an explicit 

 statement as to whether he has himself obtained 

 this scale. In one of his papers in the Monthly 

 3[i.croscopical Journal he tells us that LepUlocyrtus 

 cia-cicollls, if kept alive, will, as it grows old, 

 develop the " test scale," But this he qualifies by 

 adding the words, " at least I think so,"- a highly 

 important qualification, as it implies that, as a 

 matter of fact, he has not found it to be so himself. 

 Perhaps from his subsequent experience he could 

 now say whether it is so, or whether the species 

 is distinct, and can be found. Considering the 

 number of persons interested in the clothing of 

 these small deer, it certainly seems strange that 

 this information is so difficult to be had. And if 

 the species is distinct, and there was but one colony, 

 it was a curious coincidence that Mr. Beck, who 

 happened particularly to wish for them, should also 

 be the person to find them,— ^. L. B. 



How TO OBTAIN DiATOMS IN A StATE OF 



Pliuty,— The Jmerica/i Journal of Microscopy ve- 



commends as the best plan " of collecting Diatoms 



, in large quantities, to tic a thin fine piece of muslin 



