382 PliYLUM ARTHROPODA 



either side of the head, a long coiled gland which is intracellular in 

 type. It is largest in the so-called " nurses " which feed the young, 

 and diminishes in size later. According to Mr. Cheshire, this gland 

 secretes a nitrogenous fluid which is furnished to all the larvae in their 

 early stages, but is supplied to the future queen during the whole of 

 the feeding period, and also during the period of egg-laying ; this 

 secretion was formerly termed " royal jelly." It is this differential 

 feeding which determines the appearance of the specialised queen ; in 

 the earliest stages, queen and worker larva? are identical. In addition 

 to this pair of glands, there are in the worker three other gland systems. 

 Of these, the second and third pairs have a common central outlet on 

 the mentum, and secrete the saliva, which is plentifully mixed with 

 the nectar during suction. The fourth pair is small, and the ducts 

 open just within the mandible. The last three pairs of glands are 

 found also in drone and queen. 



The method of feeding in the bee differs considerably 

 in the three types. In the worker, the nectar sucked up 

 from flowers is mixed with sahva, passes down the gullet 

 into the crop, thence by the opening of the " stomach 

 mouth " it may reach the true stomach and so be digested, 

 or may be carried in the crop to the hive, and there emptied 

 into the cells by regurgitation. The carbohydrates of the 

 nectar are altered by the bee's digestive enzymes, cane- 

 sugar being split or " inverted " into glucose and fructose, 

 while starch is converted into gummy dextrin. The 

 pollen, which is frequently mixed with the honey, is separ- 

 ated from the latter by means of the stomach mouth, and 

 is digested. Before impregnation, the queen, like the 

 worker, feeds on pollen and honey ; after it, she is always 

 fed by the attendant workers. The drones, like the young 

 workers, avail themselves of the general food-supply of the 

 colony, and do not themselves collect honey. 



Other systems. — The respiratory system is represented 

 by the ramifying tracheal tubes. They open to the ex- 

 terior by the lateral spiracles, which can be completely 

 closed. In connection with the tracheae there are large 

 air-sacs. 



The circulatory system is in essentials the same as that 

 of the cockroach. The blood contains a few nucleated 

 amoeboid corpuscles. 



The excretory system consists of numerous fine Mal- 

 pighian tubules which open into the small intestine. 



Reproductive system. — In the drone the reproductive 



