If fertile eggs are to be prepared for a collection, they must be killed. This is easily done by thrusting into each one the point of a very fine needle, or by immersing them for a moment in boiling water, or by shutting them up in a bottle with camphor. In drying they often contract more or less, and frequently change their colour; still these are useful, providing notes have been taken of the characters thus lost. The larger eggs are capable of special treatment where the owner has the necessary time and patience, and where the highest results are desired. By means of a surgeon's injector of small size the contents of the eggs can be removed; and then, by the same instrument, a warm solution of gelatine, coloured in such a way as to restore the natural tint, may be forced into the empty shell. As the gelatine cools and hardens, it prevents any shrinking of the shell, and thus both form and colour are well preserved. For the preservation of larvae you will require one or two simple appliances. The first of these is a suitable glass blowpipe, one form of which is here illustrated. It consists of a glass tube, one end of which has been drawn out very fine; a piece of watch spring tied to it in such a manner that it will hold the skin of a larva at the small end, and a piece of india-rubber tubing at the other end, pressed by means of a brass spring clip. [Illustration: FIG. 64.--A BLOWPIPE FOR LARVAE.] A little drying oven is also very useful, but not absolutely necessary. If you decide to have one, any square box of sheet iron (not soldered tinned iron) may be readily converted into one. It must be provided with a hinged door in the front with a ventilator at the bottom, a hole for the escape of hot air at the top, and a tripod wire stand inside on which to rest the specimens while drying. The whole should be supported on a wire stand, so that heat may be applied below. Each larva to be preserved should be dealt with in this way. First kill it by means of any one of the killing bottles or boxes already described, or by immersion in spirit of wine. When quite dead, enlarge the anal orifice by thrusting a needle into it, and then lay it on a piece of blotting paper with its head toward you. Now take a round ruler, previously covered with blotting paper, and roll the larva gently from head to tail till all the contents of the skin have been expelled. Next fix the skin on the fine end of the blowpipe, by thrusting the point of the latter into the opening, and allowing the spring to press gently on its edge. Gently blow into the skin till it is inflated just to a _little below_ natural size, then either hold it near a fire or rest it in the drying oven till it is quite dry and rigid.