INTRODUCTION n 



The tongue (Fig. 25, p. 145), using the term in 

 its wider sense, is a complex structure consisting of 

 an outer and an inner pair of sheaths, the maxillae 

 and the labial palpi, which enclose the true tongue, 

 this being in the humble-bee and its allies a long 

 hairy organ having a groove on its under side. The 

 honey is sucked up by the dilatation and contraction 

 of the groove and of the tube made by the sheaths 

 around the tongue. When not in use the whole 

 apparatus is neatly folded away under the head. 



Humble-bees breathe, not as we do through 

 openings in the head, but through small holes in 

 the sides of the body, called spiracles, of which 

 there are two pairs in the thorax and five pairs (in 

 the male six) in the abdomen. The spiracles of the 

 thorax, which are situated under the wings, contain 

 a vocal apparatus which is the source of the buzzing 

 sound made by the humble-bee when it is irritated. 

 Just inside the spiracle the windpipe is enlarged to 

 form a sounding-box, and the sound is produced by 

 the air expired passing over the edge of a curtain- 

 like membrane fixed across the mouth of the sound- 

 ing box. During the buzzing the wings, it is true, 

 vibrate or quiver and increase the sound, but if they 

 are removed the sound is still produced, while if 

 the thoracic spiracles are covered, as Burmeister 

 showed, the buzzing ceases or becomes so feeble 

 that it is scarcely perceptible. 



Other organs will be considered as occasion 



arises. 



