124 ;-> MICROSCOPIC ILLUSTRATIONS. 



port of the instrument, and being independant of it, all 

 straining upon the microscope is avoided, and the stage 

 may be inclined without disturbing the hands. This 

 will be found to have a two-fold advantage ; for, by in- 

 clining the instrument, the operator is placed more at 

 his ease ; and the superfluous matter can be easily drained 

 away, which is necessary when large insects are being 

 dissected. For dissecting these objects, thin pieces of 

 soft wood, having brass rings cemented to their under 

 sides, and being fitted into the moveable or other stage, 

 will be found extremely convenient. 



The integuments of these creatures, as soon as they 

 are laid open, should be pinned down upon the wood, 

 while the nervous, respiratory, or alimentary organs 

 are being removed. The fatty matter, so very abundant 

 in insects, must be washed away with a camel-hair 

 pencil. By forming a ledge round the wood with a 

 little wax, the creature may be dissected under water 

 or diluted spirits. 



The arm, a, having an universal joint, may be turned 

 about in any direction ; and should any remarkable 

 feature present itself whilst dissecting, which it is de- 

 sirable to examine without removing it, this may be 

 readily effected by taking off the screw- nut, #, and substi- 

 tuting the usual arm of the microscope, with the achro- 

 matic body. 



Sometimes the achromatic body is employed in making 

 dissections ; in this case, the image being inverted, it 

 requires some practice in using the dissecting instru- 



