NERVOUS AND ALIMENTARY SYSTEMS. 301 



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. Ramifying 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. There is no trace of sting in the drone, 

 as is natural when we consider that it is merely a modifica- 

 tion of an ovipositor. 



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-cesopha- 

 geal 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 antennae, which are 

 furnished with numerous sensitive structures. 



Alimentary System. 



The oesophagus is a narrow tube which runs down the 

 thoracic region. In the abdominal region it expands into 

 the crop or honey sac. The crop opens by a complicated 



