100 Thf Preparafiov of CoecUlae 



Let ns suppose tliat we have some dried leaves or twigs infested with 

 a species of Lecanium. Detach a few of the insects by means of a needle 

 or fine scalpel, taking care not to injure the margin in so doing. Select 

 examples of different stages of growth, and take more than will be actu- 

 ally necessary for the final mount. Some of them are sure to be imper- 

 fect and may be discarded during the later stages of the preparation. 

 Place the selected specimens in a small evaporating dish, together with 

 a tiny fragment of pumice stone (to prevent too violent ebullition). 

 Add about two teaspoonfuls of strong potash solution and heat over a 

 spirit lamp for from two to five minutes, agitating the vessel slightly 

 and regulatingits distance from the flame so as to keep the liquid simmer- 

 ing rather than actively boiling. If it is necessary to prepare several 

 different species at the same time, specimens of each may be isolated 

 in small test-tubes (with the requisite amount of potash), plugged with 

 cotton wool and placed erect in a small saucepan containing water, the 

 whole being boiled together. The specimens must be examined at 

 intervals and removed so soon as they begin to show signs of clearing. 

 The right moment can only be learned by experience. If not treated 

 long enough, there will be subsequent difficulty in removing the contents 

 of the body If treated for too long a time, the cuticle will become too 

 tender and will tear or break up during subsequent manipulation. 



During this process, note any colour given off bv the objects. Certain 

 species colour the liquid pink — or even crimson ; others give off a 

 greenish, brownish, or inky stain. A knowledge of such characteristics 

 may be of assistance in differentiating between closely allied species. 



Remove the prepared specimens, by means of the section lifter, to 

 distilled water. Here, by a process of osmosis, further clearing will 

 take place and part of the contents of the body will pass out into the 

 water. I find it convenient to leave the objects in this medinm for 

 24 hours, and I use the excavated glass blocks for their reception. 



At this and all subsequent stages care must be taken to label the 

 specimens in such a manner that they mav l)e idontifitMl with the material 

 from which they have been taken. This label should bo traiisf erred 

 from vessel to vessel at each subsequent transference of the specimens. 

 Failure to observe this precaution may lead to most unfortunate mis- 

 takes. 



Before further treatment, note the form of the itisect wliich will 

 often have become distended to its fullest extent, when it may show 

 characters that will be lost under subsequent compression. For in- 

 stance, the lateral tentacular processes characteristic of the living 



