THE society's NOTE-BOOKS. 121 



of water, make an incision along the back of the insect (end to 

 end), and then gently wash out the inside. By doing this, you not 

 only get the tracheal system, but also the skin, which you can 

 mount, whole or in parts. If you wish, you can stain the tracheae 

 with carmine or logwood, but I have not met with very good 

 results. 



C. C. BosE. 



Feet of Blow-Fly.— I insert this slide, thinking it will probably 

 incite members to look up the subject of Feet of Insects. It is 

 quite clear, from the vast array of hairs on the feet of Diodria 

 riifipes, which is in the same box, that the creature cannot use 

 them as "suckers," and if anyone will examine the feet of the 

 common house-fly, I think they will be convinced that it does not 

 walk on glass by any sort of atmospheric pressure. Such crea- 

 tures can walk as easily in the exhausted glass of an air-pump as 

 in a common tumbler. But put them, first, into a box containing 

 any very fine powder — say, carbonate of magnesia — they will be 

 unable to walk up any glass at all. Watch them, and they will be 

 seen to wipe their feet in their own peculiar way. The insects 

 know when the very sticky hairs on their feet are clogged with 

 dust and cleanse them duly. But there are insects which have 

 regular sucker-feet ; of these I now say nothing. An observer 

 will soon notice that the hairy part, which I will call the boss or 

 brush, is sometimes of considerable size and length, and the crea- 

 ture — unless there were a special apparatus for the purpose — 

 could no more put the pad down flat than we can hold out a 

 newspaper level by holding it by one corner; it would fall thus T, 



instead of remaining thus . To effect the desired end, 



i.e.^ of keeping the brush flat — there is a variety of contrivances, 

 and into these our members will do well to pry. In the feet of 

 Diodria may be seen two rigid rods ; in the Blow- Fly there is an 

 elaborate appearance, consisting of strong ribs and a number of 

 minute rods proceeding therefrom. To describe much more 

 would be to deprive microscopists of a great pleasure. I will only 

 say that the foot of the Wasp, Bee, and Hornet puzzled me for 

 years. I never could make a satisfactor}' slide. A friend at last 

 gave me one, in which the pad was unpacked. 



Thos. Inman. 



Feet of Insects. — The Diodria^ alluded to by Dr. Inman, is 

 mounted in glycerine jelly, and it is this which causes the pulvelli 

 to show so well. I believe that the pads of insects' feet are of 

 glandular structure, and that they secrete a mucus (like that of 



