April 1, 1865.J 



SCIENCE-GOSSIP. 



Fig. 5. 

 called liouse-ily is upoiL the average of six to one in 

 my little compartment. 



Ish: Sam-aeison and Dr. Hicks pnblislied in 1858 

 a small but interesting book in a series of eight 

 letters upon the "Common House-Fly," and as 

 number one and two of mine represent theirs in 

 every particular, with the exception of number two 

 bringing forth a live grub, I would wish to ask to 

 what class we are to place number two and three — 

 are they also to represent the common house-fly ? 

 If so, we have three distinct varieties, and in all 

 probability many others. 



It occurred to me, and also to several of your 

 subscribers, that a paper upon this subject might 

 not be altogether uninteresting or out of place in 

 your instructive Science Gossip, as it may lead some 

 one more able than myseK to solve the problem. 



In the same series of letters to which I have made 

 reference, the facets in the eyes of various insects 

 are enumerated ; among the number mentioned is 

 that of the dragon-fly {Libellula). I believe it is 

 not generally known, or perhaps only known to 



EiG. 6 



myself, as I have never heard it mentioned, that the 

 eye of the di'agon-fly consists of three distinct sepa- 

 rate layers, which may with careful manipulation be 

 separated, showing the facets more distinctly. I 

 have one so obtained mounted for the microscope. 

 I acknowledge it will require a very steady hand, a 

 little skill, and plenty of patience. It is more than 

 ten years since I made this discovery, and perceiving 

 that no naturalist mentions the circumstance, I 

 thought it might be interesting to those who are 

 fond of insect anatomy, 



I will also mention another object which will 

 richly repay the trouble of mounting : the gizzard of 

 the flea, thoroughly cleansed and skiimed, is a most 

 splendid object for an § objective (mounted in 

 Canada balsam). R. S. Boswell. 



[iV.i?.— Our correspondent's drawing was too rough 

 for engraving, and we have substituted the tongue 

 of the drone-fly, which he states his own much 

 resembled, except that it was smaller, and more 

 opaque in the trunk. — Ed, So, 6^.] 



