INSECTS 133 



siderably less for the queen. When the metamorphic changes have 

 been completed, a substance is secreted by the pupa which dis- 

 solves a portion of the cocoon and permits the adult to emerge. 

 In many Insects the adult condition lasts only a short time. It 

 has as its chief function the reproduction of the species. No 

 growth occurs in either the pupa or adult stages. 



The process of egg laying and development continues until the 

 hive becomes overcrowded. When this occurs the workers con- 

 struct one or more queen-cells, and a fertilized egg is deposited in 

 each by the queen. It is known that a larva which develops from 

 one of these eggs is fed by the workers with a much richer type 

 of food than are the other larvae. Apparently as a result of this 

 the embryo, instead of becoming a sexually immature worker, de- 

 velops into a sexually mature queen. 



6. Nervous System 



The nervous system shows a great similarity to that previously 

 noted in the Crayfish and Grasshopper. Altogether there are nine 

 ganglia in the central nervous system of the Bee. Two of these 

 ganglia are located in the head, two in the thorax, and five in 

 the abdomen. The first, or cerebral ganglion, constitutes the 

 brain and is situated in the head above the esophagus. It is 

 really a very highly developed nerve center — a true brain. Vari- 

 ous branches are given off from it which run to the sensory organs 

 of the head, particularly to the eyes. Lying in the head, below 

 the esophagus, is the subesophageal ganglion, which is also 

 an important center. The nerves of this ganglion innervate a 

 number of the mouth parts. Of the two thoracic ganglia, the 

 posterior one is much the larger and gives off nerves which inner- 

 vate both pairs of wings and also the mesothoracic and meta- 

 thoracic legs. The prothoracic legs are innervated by nerves from 

 the anterior thoracic ganglion. Of the five abdominal ganglia, 

 the posterior one is very important in that it innervates the genital 

 organs and the sting. 



Sense Organs. The Bee possesses a number of sense organs 

 which are of a high type and capable of receiving various kinds 

 of stimuli from the environment. (W. f. 215.) 



(1) Tactile Organs. For the sense of touch, the Bee possesses 

 hair organs which are essentially fine projecting hairs of various 

 sizes and shapes. They have their origin in the underlying sense 



