222 THE SCOTTISH NATURALIST 



imperative that the insect to be stained be very thoroughly 

 cleared. If any vestiges of the internal tissues be left 

 within the integument they will take the stain deeply, 

 and appearing as unsightly blotches, spoil the preparation. 

 To ensure perfect transparency I usually give my specimens 

 a bath of glacial acetic acid after the KOH treatment. 

 Cole, 1 indeed, recommends the constant use of the acetic 

 bath, but most workers do not find it necessary, and I rarely 

 use it when the insect is not afterwards to be stained. The 

 following method of making stained preparations of Collem- 

 bola, with the ventral tubes extended, gives beautiful 

 results : 



Do not kill in the cyanide bottle, as the insects die in it with 

 their tubes drawn in. Either induce the insects to jump 

 into a fixing fluid, or having confined them in a small 

 specimen tube, pour in a fixing fluid. I used Carnoy's 

 fluid because it kills instantaneously. (Formula : absolute 

 alcohol, 6 parts ; chloroform, 3 parts ; glacial acetic acid, 

 1 part.) 



After four hours, replace the Carnoy's fluid, by absolute alcohol 

 to wash away the acetic acid. 



Take down to water gradually, through three or four changes 

 of diluted alcohol of diminishing strength. With specimens 

 so delicate, this caution is not superfluous. 



Leave in water till all trace of alcohol has disappeared. 



Boil in KOH 5 per cent., for one or two minutes. 



Wash in distilled water. This may be done with practically 

 no manipulation by pouring the KOH solution con- 

 taining the specimens into a little piece of " chiffon " 

 (muslin is usually too coarse), and when the fluid has 

 drained through, turning the cloth over a watch-glass 

 of distilled water in which the insects float off. The 

 distilled water may be changed several times by means of a 

 pipette. 



Substitute for the distilled water, glacial acetic acid. 



After an hour or two, add to this bath one drop of acid fuchsin 

 and leave overnight. 



Remove the acetic acid, and wash in distilled water rapidly 

 by means of a pipette. 



1 Modern Microscopy (Cross and Cole). 



