ON BEES' TONGUES, AND HOW THEY SUCK HONEY
In order to understand how a bee sucks honey it will be necessary to go into some rather careful details as to the construction of its tongue and mouth organs. These I will make as short and simple as I can, but the apparatus is a very complicated one, and it will be impossible to describe it without a good deal of technical phraseology.
The tongue has always been considered such an important feature in a bee's structure that it has been made the chief basis of their classification. On this subject I will only say that there are three principal types of tongues—a short bifid tongue (fig. 19, 3[[1]]), resembling those of the fossors; a short pointed one, shaped somewhat like a spear head (fig. 19, 2, 2a); and a long parallel-sided, ribbon-like tongue (fig. 19, 1, 1a). The bees are classified on what is considered to be an
ascending scale, beginning with the bifid-tongued species, through those with the short spear shaped tongues to the higher forms, which have this organ elongate and parallel-sided.
The tongue is the central organ of an elaborate combination of mouth parts, which I will now try to explain. If we turn a bee's head over and look at its underside we shall find a deep cavity, filled up with the base of this combination which fits into it. If we extend the tongue (a humble bee is a good subject on account of its large size, fig. 20) so as to draw its base out of the cavity, we shall find that in the edge of each side of the cavity there is articulated a short rod (20, A), more or less dilated at its apex, called
the stipes; on the flattened ends of these rods there swings a joint shaped something like the "merrythought" bone of a chicken, called the lora or reins (20, B), to the central angle of which are suspended the pieces of the apparatus which terminate in the tongue. This V-shaped joint can swing over on its feet, and can therefore lie either between the stipites or rods with its angle pointing towards the tail of the bee, or in the opposite direction with its angle projecting beyond them and pointing forwards. It will at once be seen that by this turn of the V the tongue can be projected a distance equivalent to twice the length of the V.
This V-shaped joint varies much in the length of its arms, which are much longer in the long-tongued than in the short-tongued bees.
When we examine the parts that are suspended from this joint, we shall find that the actual tongue is separated from it by two distinct pieces; the first (i.e. that next to the lora) a short joint (the submentum, 20, C), the second (the mentum, 20, D) a long semi-cylindrical joint which holds as in a trough the softer parts at the base of the tongue. From the apex of the mentum
project three organs; the central one is the actual tongue (or ligula, 20, E), and on each side are the organs which are called the labial palpi (20, F); these in the long-tongued bees more or less fold over the base of the tongue and protect it. There are two other large and important mouth parts called the maxillæ (20, G); these articulate on to the flattened apices of the cardines, outside the articulation of the feet of the lora, and extend on each side of the mentum; they also have flattened blades sheathing, when closed, the whole of the mentum above, as well as the base of the tongue.
So far we have been looking at the back of the head and mouth parts; if we now look at the front we shall see the maxillæ; if we open these we shall see the tongue lying between the
labial palpi, and at the base of the tongue we shall see two little sheaths called the paraglossæ; above these the softer parts lying in the trough of the mentum; from the base of the mentum, connecting with the maxillæ, there extends a membrane which entirely invests the spaces between the bases of these organs and extends up to the mouth. A membrane also extends between the stipites and lora, and closes the cavity at the back of the head. The back of the tongue in the act of sucking can be formed into a tube through which, partly, probably by capillary action, partly by the pumping action caused by the dilating and contracting of certain parts of the mechanism, the liquid food is drawn up into the æsophagus. This, I believe, has been shown to be the principle on which all bees, short- or long-tongued, suck up their honey. The subject could be treated at much greater length, and many other structures connected with the mouth parts discussed, but more minute details are unnecessary in an elementary work such as this, and I have therefore limited myself to a description of the broad principles of the process.