3 1 8 PHYL UM ARTHROPODA. 



at Ihe back of ihe tibia, and furnished with numerous hairs. In queen 

 and drone, Ihese special arrangements of hairs are absent. 



The second and third thoracic segments bear each a pair of wings. 

 These are largest in the drones and relatively smallest in the queen, 

 who flies but seldom. At the base of each wing there is a respiratory 

 spiracle. 



In the adult queen and worker, the abdomen is divided into six 

 segments ; in the drone, into seven. There are no abdominal appen- 

 dages. On the ventral surface in the worker, but not in the queen or 

 drone, there are four pairs of wax pockets or glands, which secrete 

 the wax, which, after mastication with saliva, is employed in building 

 the combs. The abdomen also bears in queen and worker five pairs of 

 spiracles, but in the drone, on account of the additional segment, there 

 are six pairs. The total number of spiracles is thus fourteen for queen 

 and worker, and sixteen for the drone. The posterior region of the 

 abdomen bears the complicated sting. In the worker this consists of a 

 hard incomplete sheath, which envelops two barbed darts. The poison 

 flows down a channel lying between the darts and the sheath. Ramify- 

 ing through the abdomen are found the two slender coiled tubes which 

 constitute the poison gland. At the posterior end of the body these 

 unite and open into a large poison sac. When a bee uses its sting, the 

 chitinous sheath first pierces the skin, and then the wound is deepened 

 by the barbed and pointed darts, while at the same time poison is steadily 

 pumped down the channel mentioned above, and pours out by minute 

 openings at the bases of the darts. The poison contains formic acid, 

 and is fatal to the bee if directly introduced into its blood. Associated 

 with the sting there are a pair of delicate tactile palps. In the queen 

 the sting is curved and more powerful, but it is apparently only used in 

 combat with a rival. In the worker the sting, and with it a portion of 

 the gut, is usually lost after use, and, in consequence, death ensues ; the 

 queen, on the other hand, can withdraw her sting from the wound with 

 considerable ease. The sting is really an ovipositor adapted to a new 

 function. Naturally, therefore, there is no trace of it in the drones. 



Nervous system. In the adult this exhibits considerable 

 fusion of parts. The supra-cesophageal ganglia are very 

 large, and send large lateral extensions to the compound 

 eyes. This " brain " is best developed in the active workers. 

 The sub-oesophageal mass is formed by the fusion of three 

 pairs of ganglia. In the thorax there are two pairs of 

 ganglia, of which the second supplies the wings and the 

 two last pairs of legs. In the worker there are five pairs 

 of abdominal ganglia, but in the queen and drone only 

 four. The sense organs are the simple and compound 

 eyes, and the antenn?e, which are furnished with numerous 

 sensitive structures. 



Alimentary system. --The eesophagus is a narrow tube 

 which runs down the thoracic region. In the abdominal 



