I must just tell you something of the uses of the five eyes. At one time it was supposed that each facet of the compound eyes made a separate image of the object to which it was directed. But this is very improbable, for what possible use could there be in the insect seeing, instead of the one flower at which it was looking, several thousands of flowers each exactly like the other? It is much more likely that every facet forms a picture of only that part of the object which is exactly in front of it, all the pictures combining to form a single image. No doubt the compound eyes are used for seeing things at a distance, and the simple eyes for objects near at hand.
It has been proved that bees can distinguish between colours, and even that they prefer certain colours to others; one of their favourite colours is pale blue. An experiment, which is both interesting and instructive, has often been performed, and it shows us that not only is the bee able to tell one colour from another, but also that it possesses a memory. Pieces of blue, yellow, and red paper are obtained, and upon each is placed a slip of glass. A little honey is placed upon the slip of glass which is over the blue paper, and all three are put near a hive. A bee is caught and placed on the honey. After sucking some of it she flies to the hive to store her treasure and quickly returns for more. She is allowed to make several journeys between the honey and the hive, so as to impress upon her memory that the honey is to be found on the blue paper. Then while she is away at the hive, the slip of glass is placed upon the yellow paper. She returns, as before, to the blue paper, and seems puzzled at not finding the honey there, but after a careful search, she discovers the honey on the yellow paper. The fact that the bee came back to the blue paper proves that she has a memory and that she is able to distinguish one colour from another.
CHAPTER IX
THE TONGUE AND MOUTH
PARTS
THE tongue of an insect is called the proboscis, a Greek word meaning a front feeder, or trunk, and indeed the bee’s tongue is not unlike the trunk of an elephant. Let us glance at Plate VIII., where a picture of the mouth parts of the bee is shown. The tongue itself is in the centre, and it appears long and hairy, tapering to a fine point. On each side of the tongue are the Labial palpi, which are part of the case in which the tongue is kept, when not in use. Beyond these are the Maxillæ, or inner jaws, which form the other part of the case.
Each labial palpus consists of four joints, the upper two (Nos. 1 and 2 on the picture) being much larger and broader than the lower ones, which are quite tiny in comparison. They have several hairs growing upon them, and these hairs are used for feeling. The importance of hairs to the bee is very great, and we find them all over the body. They are of different shapes and sizes, and we shall read more about them as we come to consider each kind in turn. When the labial palpi are closed, they protect the back part of the tongue, the front part being protected by the maxillæ. These four parts, when closed, make a kind of tube, in which the tongue rests. Although this protecting case cannot be drawn up into the mouth, the bee is able to draw up the tongue at will.
Plate VIII
From a photo-micrograph by] [E. Hawks
Tongue and Mouth Parts of Bee
(b) Plate VII. shows a good view of the tongue itself, as seen with a high magnifying power. It is composed of a number of ring-like structures, and is covered with hairs which are regularly placed and point in a downward direction. The tongue of the worker bee, it is interesting to note, is nearly twice as long as that of the queen or of the drone. This is because neither of the latter gather nectar, and so they do not need such long tongues as the worker. Her tongue being longer, she is the more easily able to reach the nectar, which, in some flowers, is only to be found at the bottom of a long corolla. The tongue of the worker has from 90 to 100 rows of hairs, but those of the queen and the drone have only from 60 to 65 rows each.
The tongue is extremely elastic, and is capable of being moved in any direction at will. Some of the hairs with which the tongue is clothed are of use for feeling, but most of them are for a different purpose altogether. When a bee pushes her head into the corolla of a flower, her tongue sweeps from side to side. If there is any nectar there, it sticks to the hairs of the tongue in tiny droplets, and in this way it is collected. Later on we shall find how it is dealt with after it has been gathered.