190 Modern Microscopy 



in distilled water until soft. Some specimens will only 

 require a few hours in the potash, others need days, and 

 some even weeks, to soften. In all cases they must be 

 carefully watched and the action of the potash tested. 

 This can be ascertained by pressing on the thorax or chest 

 of the insect with some blunt instrument, such as the head 

 of a pair of curved-pointed forceps. 



(3) When soft enough, pour away the potash and add 

 water, which must be changed several times until all the 

 potash is washed away. 



(4) Pour away the water and add concentrated acetic 

 acid, and soak for twelve hours, or until it is convenient to 

 go on with the work. 



(5) Transfer from acetic acid to water, and soak for 

 about half an hour ; then place in a shallow saucer full of 

 water, and with the aid of a needle and a camel's-hair 

 brush spread out the wings, legs, etc. Now take a slide 

 and place it in the water under the insect, lift the slide up 

 carefully so that the insect may be stranded on the surface 

 of the slide with all its parts expanded. Drain off the 

 excess of water, and lay the slide down on a piece of white 

 paper, and with the aid of needles or brushes carefully 

 place all the limbs, wings, antennae, etc., in their natural 

 positions. Now put a narrow slip of paper on each side of 

 the insect, and carefully lay another slide over it, press it 

 down until the insect is squeezed quite flat, tie the two 

 slides together with a piece of twine, and place them in a 

 jar of methylated spirit for at least twelve hours, or until 

 required. 



(6) Remove the glasses from the spirit, carefully separate 

 them, and with a soft camel's-hair brush push the insect 

 off the glass into a saucer of spirit. 



(7) Take the insect up on a lifter, and float it on to the 

 surface of a small saucer of clove- oil, and allow it to soak 

 until perfectly clear. 



(8) Eemove from clove-oil and place in turpentine for a 

 few minutes. 



