THE SILKWORM ITS INTERNAL STRUCTURE. 37 



pillar. This must be pinned on to the paraffin, beneath the 

 water, with a fine pin at each end of the body. Ordinary dress 

 makers' pins are too stout and not sufficiently fine-pointed to be 

 conveniently used ; the best for the purpose are "entomological 

 pins ''' which may be obtained at any naturalist's. In default of 

 these, short needles, or the pointed ends of broken ones will do. 

 The caterpillar should be fastened down firmly, and slightly 

 stretched, or there will be difficulty in keeping it sufficiently steady 

 to perform the dissection neatly. Now we shall require a pair of 

 fine-pointed steel forceps, a pair of dissecting scissors with rather 

 long handles and fine short blades, and a dissecting knife or 

 scalpel, which is simply a long-handled, thin-bladed, sharp knife. 

 All of these may be purchased at a cost of a few shillings at any 

 good optician's. Of course substitutes may be used for the two 

 latter, such as ladies' fine embroidery scissors, and a small, sharp, 

 penknife, but they will not perform the work so neatly, nor be so 

 convenient to use. Most of the following dissections, however, 

 may be performed by the help of scissors and forceps alone. 



In order to make the greatest possible use of a single dissection, 

 a blank note book, a hard, fine-pointed black pencil, and two or 

 three coloured pencils should be provided. By means of these, 

 drawings of the dissection in its various stages may be made, and 

 will be found exceedingly helpful towards really understanding 

 the creature's anatomy. If carefully made, they serve for reference 

 at any time, and are then almost as valuable as the original dis- 

 section itself. The coloured pencils are for putting in the different 

 organs in different colours, thereby to distinguish them from one 

 another more easily. It may seem at first thought that this 

 drawing must be a formidable affair, especially for those who have 

 had no instruction in draughtsmanship, and indeed some little 

 difficulty will, no doubt, be encountered at first ; but it will pass 

 away by experience, and a little practice will produce a fair degree 

 of proficiency. In all the drawings great pains should be taken 

 to make the outline of the various parts distinct and correct, and 

 the relative position of parts as accurate as possible ; minute 

 details need not be attended to at first, the aim being not simply 

 to make pretty pictures, but to show the true form and relation of 

 parts, to make the drawing a sort of key to the work, on which, 

 e.g., the names of the parts may be written. The dissection may 

 be preserved from one occasion to another, or indeed for an 

 indefinite time, by simply keeping it in spirit ; methylated spirit 

 will do very well. A pair of dissecting needles, that is, ordinary 

 sewing needles firmly fastened into wooden handles, such as are 

 used for camel's hair brushes, may usefully be added to the above 



