69 



Some Cheap Aids to Microscopical Studies. By S. J. 



McIntire. 



{Read March 27th, 1868.) 



My object in the few brief remarks I am about to make is to 

 bring forward certain cheap appliances, from which I have derived 

 great assistance in my microscopical recreations, aud which I can 

 confidently recommend to the members of this club. 



The first of these is an apparatus for the examination of such an 

 object as a hve flea, but it is available as a disc-holder in all cases 

 where the observer can dispense with the refinements of optical 

 work. It consists of a flat piece of mahogany, about four inches 

 by two inches, and one-third of an inch thick, with a perforation 

 in the centre, about 1^ inches in diameter. A little cube of cork 

 occupies the centre of the perforation, and is kept in its place by a 

 piece of straight wire passing through it and the greater part of 

 the long diameter of the block of wood. The free end of the wire 

 has a round knob on it, enabling the little cube of cork to be 

 rotated. (I use a hair pin and a glass bead.) To examine a flea, 

 I first stupify it with chloroform, and then fix it to the cube in the 

 position desired with a little strong gum arable. By the time the 

 gum is hard the effects of the choloform have passed off, and then 

 a better view of a flea is obtained with the assistance of the two- 

 thirds objective and Lieburkuhn than by any other means that I am 

 acquainted with.* This apparatus may be used with advantage in 

 the attempt to penetrate the mystery as to the functions of the 

 pygidium. I was told that the pygidium is an organ of sensation, 

 and that by blowing gently upon the insect, the long hairs from 

 the centre of each of the areola in that object would vibrate. The 

 vibration may certainly be seen, but as it is also to be produced by 

 similar means after the death of the flea, it is not to be considered 

 demonstrative proof of this supposed function ; though I think it 

 probable that the theory is true. By the time the discussion on the 

 subject takes place at this club, perhaps some members may be able 

 in consequence of their investigations, to give an opinion. 



The second piece of apparatus is one for the examination of a 

 tadpole, and I have the permission of the inventor, Mr. Alexander 

 * I borrowed the hint from Mr. Archer. 



