GENERAL BIOLOGY 



Fig. 235. 



A. Nervous system of honey-bee, at a., and of 

 its larva, at 6., showing the simple type of the larva 

 and the specialization in the adult due to fusion of 

 the ganglia. (From Sanderson and Jackson, "Ele- 

 mentary Entomology/' by permission of Ginn & Co.) 



C. Nervous system of the head of cock- 

 roach, a., antennal nerve ; ag., anterior later- 

 al ganglion of sympathetic system ; 6, brain 

 d. t salivary duct ; /., frontal ganglion ; h. 

 hypopharynx ; 1., labrum ; li., labium ; m. 

 mandibular nerve ; mx., maxillary nerve ; nl. 

 nerve to labrum ; nli., nerve to labium ; o. 

 optic nerve ; oc., oesophageal commissure ; oe. 

 oesophagus ; pg., posterior lateral ganglion of 

 sympathetic nervous system ; r., recurrent 

 nerve of sympathetic system ; s., suboeso- 

 phageal ganglion. (After Hofer.) 



B. Sympathetic nervous system 

 of an insect, diagrammatically rep- 

 resented, a., antennal nerve ; 6., 

 brain ; /., frontal ganglion ; l.L, 

 paired lateral ganglia ; m., nerves 

 to upper mouth-parts ; o., optic 

 nerve ; r., recurrent nerve ., nerve 

 to salivary glands ; st., stomachic 

 ganglion. (After Kolbe. ) 



system is made up of the many 

 fibers which pass to all parts of the 

 body from the triangular ganglia 

 lying in each segment. 



ORGANS OF SPECIAL SENSE 



These have already been dis- 

 cussed very thoroughly under the 

 general term, "The Senses of In- 

 sects," in Chapter XXIII. 



THE MUSCULAR SYSTEM 



As in the crayfish, the muscles 

 of the honey bee are attached to the 

 inner walls of the body. The num- 



ber of muscles is very large, and the 

 largest muscles are those which move the wings and legs. 



Muscles are both voluntary and involuntary. A good example of 

 the latter has already been noted in the experiment suggested of the 

 intestine being placed in a one-half of one per cent salt solution when 

 the lips of the stomach-mouth will open and close for some time. 



Insects usually have much greater muscular strength proportion- 

 ately than larger animals. This is accounted for by the fact that the 

 weight of muscle increases as the cube of its diameter, while its strength 

 increases only as the square of its diameter. 



