356 



HALF IlOUPtS WITH IXSECTS. [Packard. 



Fig. 260, copied from a drawing by Prof. Leidy, repre- 

 sents the nervous system of a neuropterous insect, the Coiy- 

 dalus, figured on page 151. The central nervous system is 

 a double cord enlarged at intervals, forming nerve centres 

 or ganglia, of which there are sometimes thirteen pairs. A 

 Fig. 260. Russian anatomist, OfTsianni- 



koff, has found that the gan- 

 glion of a spiny lobster {Pali- 

 mirus) is composed of nucle- 

 ated cells, from which arise 

 ver}' long fibres which are gath- 

 ered into bundles, forming the 

 nerves ramifying tlu'oughout 

 the bod}'. There is thus a 

 direct physical communication, 

 telegrnphic Avires, as it were, 

 loading from all parts of the 

 body to these nerve-centres. 

 Of these there are two pairs 

 lodgctl in the head ; the most 

 anterior, those situated in the 

 top of the head, are the larger 

 and are for convenience called 

 the bi-ain, but it will be seen, 

 that though thc}^ are a little 

 larger they do not differ from 

 the other pairs of nerve cen- 

 tres. From this so-called brain 

 are distributed nerves to the 

 Nervous System of Corydaius. antenuffi, the palpi and jaws ; 



a large thick nerve sent to the eye is the optic nerve (a). 

 From the other nerve-centres filaments are thrown out to 

 the wings, legs, muscles and vessels in the body. We shall 

 see that these centres are really so many brains, and that 

 insects differ in this respect from the vertebrate animals in 



4 ' 



