340 



GENERAL BIOLOGY 



the body in the same way. These tubules ramify throughout the body 

 in the animal and are very conspicuous when the body is opened. 



THE NERVOUS SYSTEM 



The nervous system closely resembles that studied in the crayfish, 

 there being a series of ganglia along the ventral nerve cord which split 



Fig. 222. 



Reproductive system of the Queen honey 

 bee. a, accessory sac of vagina ; b, bulb of 

 stinging apparatus ; c, colleterial, or cement 

 gland ; o, ovary ; od, oviduct ; p, poison glands ; 

 pr, poison reservoir ; r, receptaculum seminis ; 

 re, rectum; v, vagina. (After Leuckart). 



Fig. 221. 



A, diagram to illustrate the action of 

 wing-muscles of an insect. 



B, diagram of wing-muscles, a, alimen- 

 tary canal ; en, muscle for contracting thorax, 

 to depress wings ; d, depressor of wing ; e, 

 elevator of wing ; ex., expander of thorax to 

 elevate wing ; id, indirect depressor ; ie, in- 

 direct elevator ; I, leg muscle ; p, pivot or ful- 

 crum ; s, sternum ; t, tergum ; wg, wing. 

 (After Grabers). 



at the oesophagus, one-half of the cord passing dorsalward on each side 

 of that organ, uniting again on the dorsal surface and forming the supra- 

 oesophageal ganglion or brain, while the ganglion below the oesophagus, 

 which branched to permit the passing around to form the brain, is known 

 as the suboesophageal ganglion. It is from the brain that nerves go for- 

 ward to supply the special sense organs, such as the eyes, antennae, and 

 labrum, while the mandibles and maxillae are supplied from the sub- 

 oesophageal ganglion. 



Nerves are given off from the thoracic and abdominal ganglia to all 

 parts of the respective segments. The interesting thing about insects 

 is that these nerve centers seem to be as independent as are the separate 

 respiratory tracheae in that the head may be removed while the other 

 parts of the body continue their work almost as well as before. In addi- 

 tion to the Central Nervous System and the regular Peripheral Nervous 

 System, consisting of these segmental nerve filaments, there is also a 

 Sympathetic System, divided into two parts, one lying dorsal to the ali- 

 mentary tract and controlling processes while the other lies ventral to 

 the alimentary tract and controls the spiracle muscles. 



