48 THE ANATOMY OF THE HONEY BEE. 



ward and has two muscles attached to it. This is shown by figure 

 15 H, where the rod (r) is torn from the glossa {Gls) basally so as 

 to show the muscles {2RMcl) inserted upon it and its connection 

 with the plate (o). By the contraction of the muscles the rod bends 

 at its base and is drawn back into the mentum. The glossa thus 

 shortens and becomes bushy just as does a squirrel's tail when one 

 attempts to pull the bonp out of its base. 



The protrusion of the parts is due to the pressure of blood driven 

 into the ligula from the mentum, Avhile probably the glossa extends 

 also by the straightening of its rod as the muscles relax. Wolff 

 described a protractor muscle at the base of the ligula. The rod of 

 the tongue is certainly not in itself contractile, as supposed by 

 Cheshire, who looked for evidence of muscular striation in it. It has 

 mostly a transparent and cartilaginous appearance, but is presumably 

 chitinous. 



The mouth parts, their action in feeding, and the muscular mech- 

 anism by which they are moved have been elaborately described 

 and illustrated by Wolff (1875) in his monograph on the organs of 

 smell in bees. Most unfortunately, however, Wolff's paper was 

 written to show that the seat of the sense of smell is in the mouth, 

 a most erroneous notion, and the title of his paper based on this 

 notion has caused little attention to be paid to this work on the mouth 

 parts of the bee, which is one of the best anatomical treatises evei' 

 produced on the mouth parts of any insect. 



It, still remains for us to describe the details of the glossa and its 

 particular function in feeding. The tongue is not a solid appendage 

 nor yet is it truly tubular. A. compromise is effected by the longi- 

 tudinal groove (fig. 15 A and D, k) on its ventral surface which 

 expands within the tongue into a large cavity occupying half of its 

 interior (E, Lum). The glossal rod (r), which has already been 

 mentioned, lies in the dorsal wall of this channel and is, hence, 

 really not an internal but an external structure. The rod is itself 

 grooved along its entire ventral length (E, I) and this groove agaiii ■ 

 is converted into a tube by two rows of short hairs which converge 

 from its margins. The lips of the ventral groove of the glossa are 

 so deeply infolded that its cavity is almost divided along the midline. 

 Hence, the glossa might be described as containing three channels. — 

 a small median dorsal one (?) and two large latero- ventral ones 

 {Lum). 



The glossal rod (fig. 15 C, r) is very flexible but not contractile, as 

 already stated, and is mostly clear and cartilaginous in appearance, 

 its ventral groove {I) alone being lined by a deposit of dark chitin 

 (fig. 15 C and E). Its shape in section is sufficiently shown by the 

 figures. The walls of the large channels of the proboscis consist of 

 a delicate membrane (C and E, q) covered with very small hairs. 



