Microscopists who care to follow up the study of insects’ mouths will know that they are accumulating really useful knowledge. Those who do not desire to go so deeply into the matter may well spare a few moments for the examination of the green fly mouth, a needle-like piercing organ which is thrust into plants for the purpose of sucking their sap. The mouth of the gnat is a more difficult subject for the microscopist, though no less interesting; it may be compared with the same organ of the green fly, for it is used somewhat similarly, with the difference that it sucks blood and not plant juices. It may be well to mention here that the females alone suck blood, but it is easy to distinguish the sexes, for the antennæ or feelers of the females are thread-like whilst those of the males are feathered. A few adult insects have no mouths, for they never feed during their short lives. Caterpillars of all kinds and also beetles, grasshoppers, cockroaches and the like have biting-mouth parts, and the student, who is not well versed in insect anatomy, will learn more by watching one of these insects partaking of a meal than by trying to discover the uses of the various parts with the aid of a microscope. Caterpillars as a rule are not shy feeders, and a pocket lens will show their sickle-like jaws in full play. The grubs of house-flies are worth examining; they are soft and fleshy except for a pair of horny hooks which are used to tear up the food material. There are, however, so many different mouths we cannot describe even the typical ones, but the microscopist will soon discover those of special interest. The feet of insects do not show so much variation as their mouths, nevertheless they will afford ample material for many hours of study. Our butterfly, which is now but a remnant, will provide our first object. The design of its feet will depend, to some extent, on the species of insect, but they will certainly be clawed. Other insects with clawed feet--beetles, bees, and wasps--may be examined, and we shall see that there are minor differences amongst them though their general plan is similar. Sometimes we find a simple pair of claws on each foot, in other cases each claw has a little spur, whilst spiders, which, by the way, are not insects, have comb-like claws. The foot of the house-fly is not only provided with a pair of claws, but also with a soft fleshy pad, by means of which it is enabled to climb window panes and similar smooth surfaces. If we are fortunate enough to obtain a specimen of a louse, human or otherwise, we must not fail to notice its strong grasping claw, used for taking a firm hold of the hair of the creature on which it lives. Such objects are better examined under a high magnification, along with a hair, then the actual method of grasping may be observed.