Fig. 9 shows the penetrating portions of the sting of the wasp. The two barbed stings, which seem to be the minute prototypes of the many-barbed spears of the South Sea islanders, are seen lying one at each side of their sheath, and a single barb is drawn a little to the left on a very much larger scale. It is by reason of these barbs that the sting is always left adhering to the wound, and is generally drawn wholly out of the insect, causing its death in a short while. The sting is only found in female insects, and is supposed to be analogous to the “ovipositor” of other insects, _i.e._ the instrument by which the eggs are deposited in their places. Fig. 20 shows the curious egg-placing apparatus of one of the saw-flies. The backs of these “saws” work in grooves, and they work alternately, so that the fly takes but a very short time in cutting a slit in the young bark of a tender shoot, and laying her eggs in the slit. When she has completed one of these channels, she sets to work upon another, and in the early spring the young branches of the gooseberry bushes may be seen plentifully covered with these grooves and the eggs. When hatched, black caterpillar-like grubs from the eggs issue, and devastate the bushes sadly, turning in process of time into blackish flies, which are seen hovering in numbers over the gooseberries, and may be killed by thousands. * * * * * The scales and hairs of other animals deserve great attention. Fig. 23 is a single hair of the human beard, as it often appears when tied in a knot--by Queen Mab and her fairies, according to Mercutio. Fig. 22 is a portion of the same hair as it appears when splitting at its extremity. The structure of the hair is not, however, so well seen in this object as in that represented on Fig. 24, which is a beautiful example of white human hair that once adorned the head of the victor of Waterloo. It formed one of a tiny lock given to me by a friend, and is so admirable an example of human hair, that I forthwith mounted it for the microscope. In this hair the cells may be seen extending down its centre, and the peculiar roughened surface produced by the flattened cells which are arranged around its circumference are also seen. By steeping in caustic potash, these scales can be separated, but generally they lie along the hair in such a manner that if the hair be drawn through the fingers from base to point, their projecting ends permit it to pass freely; whilst if it be drawn in the reverse direction, they cause it to feel very harsh to the touch. In the sheep’s wool (Fig. 30) this structure is much more developed, and gives to the fibres the “felting” power that causes them to interlace so firmly with each other, and enables cloth--when really made of wool--to be cut without unravelling. Fig. 37 is the smooth hair of the badger; and Fig. 34 is the curious hair of the red deer, which looks as if it had been covered with a delicate net.