The pad is called the “pulvillus,” and is close to the claws. We all know how easily a fly can walk upside down on the ceiling, or run up a window pane. It is able to do this by means of pads which it also possesses. These pads are covered with a kind of gummy liquid, and by their aid a fly or a bee can walk up, or perhaps it would be more correct to say stick to, a window pane or other smooth surface. The fly, however, can beat the bee when walking on such surfaces, because it has two pads on each foot, whereas the bee has only one. On the other hand, the claws of the fly have no hooks, therefore flies cannot cling to each other as bees do. It is very interesting to understand how the pads are brought into use by the bee. You must remember that they are placed just above the claw itself; when the bee is walking over an uneven surface the claw catches on the roughnesses, and then the pad remains in its ordinary position. When the bee comes to a slippery surface, however, the claw is not able to obtain a grip, and so it slips down under the foot, its place being taken by the pad. This presses against the smooth surface and adheres to it by means of the sticky moisture with which it is covered. Here is a sketch showing the pad just coming into action. [Illustration] The pads hold very tightly on to a smooth surface when they are pulled _downwards_, as it were, by the weight of the bee. But they are very easily loosened if the sides are lifted up, and in this manner they may be peeled off the smooth surface, just as we take a stamp off a letter. So beautiful is this arrangement, and so perfect in its action, that it is stated a bee can put down and lift up each foot at least 1200 times a minute! CHAPTER XIII THE FIRST PAIR OF LEGS The first pair of legs, or those nearest the head, are the shortest of all. The most interesting feature about these legs is a little semi-circular notch, and I have made this sketch of it. [Illustration] Under the microscope we see that around the semi-circular opening is a row of about eighty teeth. These are not biting teeth, but are more like the teeth of a comb, and indeed this notch is a comb which is used for cleaning the antennæ. You may sometimes see a bee bring up its front leg to its head, and then move the leg outwards. By this movement the antenna is drawn into, and through the comb, the teeth of which soon remove any dirt or pollen which may be sticking to it. Just above the antenna comb, there is a kind of little hinge or lid. This is called the “velum,” and its name comes from a Latin word meaning “to cover,” for the lid covers the antenna when it is drawn into the comb, and holds it there whilst it is being pulled through. When we know that each antenna is only 1/125th of an inch in diameter, we can understand what a wonderful little tool the comb is.