4 Transactions. — Zoology. 



them in strong liquor imtasscR. For this purpose I use a small 

 shallow dish placed on a flat tin plate over a spirit-lamp. The 

 duration of this boiling should vary with the size of the insect : 

 a small Asjndiotus or a moderate Eriococcus will require much 

 less time than one of the large Coclostovias. Practice again 

 will show when to remove the lamp. The action of the potash 

 is exercised mostly on the soft internal organs. If the boiling 

 were continued long enough, the chitinous epidermis and the 

 feet and antennae would be destroyed also, but it will soon be 

 ascertained when the internal portion is sufficiently softened, 

 leaving the epidermis unharmed. In the case of a large insect 

 it is usually better to prick it with a needle in two or three 

 places so as to allow the internal substance to wash out. 

 Thirdly, pour away the superfluous liquid, and replace by cold 

 water. One thing is specially to be avoided — namely, any 

 ■touching of the insect which can possibly be done without, as 

 loiag as any potash remains to soften it. Fourthly, float the 

 insect carefully from the dish on a glass slide, with plenty of 

 water ; place a thin cover-glass on it, and very gently press it 

 down : this very slight pressure will usually suffice to expel 

 the greater part of the internal substance without materially 

 injuring the specimen. If now the insect be looked at with a 

 lens it will be found that the boiling in potash has not only 

 rendered it sufficiently transj)arent to show all the organs, but 

 has at least nearly restored it to its proper shape — -taken out, 

 as it were, all the creases. Fifthly, fl.oat the specimen from 

 the glass slide, cover and all, into a wine-glass of clean water : 

 the cover will float away, the specimen will leave the slide ; 

 and now wash it thoroughly in the water, taking care not to 

 touch it with anything hard. Sixthly, when well washed, 

 with all the potash out of it, float it again on a slide, pour ofi^ 

 the water, and replace it with strong alcohol : let the insect 

 soak thoroughly in the spirit, and after a few minutes it will 

 be found sufficiently hard to be gently moved with a camel's- 

 hair brush into the centre of the slide where it is to remain 

 permanently. Seventhly, put on the required thin cover-glass 

 properly centred ; run in more alcohol so as to keep the speci- 

 men well soaked ; and now it can be examined under the 

 microscope, the various organs noted, and its characters 

 thoroughly ascertained. In general, it is best to place the 

 specimens on the slide with the ventral surface uppermost, as 

 most of the organs are on that surface ; but sometimes the 

 reverse is required. Now put away the slide to dry ; and it 

 will be well to leave it for several hours with this object, so 

 that every particle of the alcohol may evaporate. The cover- 

 glass will prevent the specimen from shrivelling up or be- 

 coming dusty. Lastly, and preferably next day, when it is 

 quite dry, run in under the cover-glass a drop or two of 



