If you have done your work neatly, the skin and blowpipe will both be quite air-tight when the clip is closed; and the air, finding no outlet, will still further inflate the skin when it expands on exposure to heat. This is the reason why you are directed to blow it out to something short of the natural dimensions. If you find that this expansion causes the skin to stretch beyond its normal size, a little of the air must be allowed to escape while it is yet soft and flexible. The front of the larva is generally the last portion to become dry, and when this is quite rigid the skin may be removed from the blowpipe. This is a matter that requires the greatest care; for the skin is so very thin and brittle that a little rough handling will break it to pieces. As a rule it may be easily pushed off the pipe by a slight pressure behind, or a gentle twisting motion will loosen its hold; but this latter method can hardly be applied to hairy larvae without breaking off the hairs, now rendered very brittle by the heat. If you find the slightest difficulty in detaching the skin of a valuable specimen, it is far better to damage the blowpipe than to risk spoiling the skin. Supposing your blowpipe is a glass one, you can easily break off the end of it after making a cut with a very small triangular file, and the portion thus removed may be left attached to the skin. Then, after softening the glass blowpipe in a gas flame or the flame of a spirit lamp, it can be drawn out thin again for future work. Those who can manipulate glass tubing in this way will find it far better to lay in a stock of suitable material, drawing it out when required, than to purchase blowpipes ready made at the naturalist's shop. Very fine hollow stems, such as those of the bamboo cane, may be used instead of glass; and these possess the advantage of being easily cut with a sharp knife when there is any difficulty in removing the skin. Again, whether glass or fine stems are used, a little grease of any kind placed previously on the end will allow the dried skin to be slid off with less difficulty. Preserved larvae should preferably be mounted on small twigs or artificial imitations of the leaves of the proper food plants. A little coaguline applied to the claspers will fix them very firmly on these twigs or leaves, which are then secured in the cabinet by means of one or two small pins. It is much to be regretted that the natural colours of many caterpillars cannot be preserved in the blown skins. Some are rendered much lighter in colour on account of the withdrawal of the contents, while others turn dark during the drying. In the smooth-skinned species the natural tints may be restored by painting or by staining with suitable aniline dyes, but these artificial imitations of the natural colours are always far less beautiful than the hues of the living larvae.