240 ANIMAL PHYSIOLOGY. [LESSON 72. 



elongated, and obscurely divided by a slight median indentation into 

 two side-lobes ; its upper and latter extremities are prolonged out- 

 wards into the optic lobes (c, c), which resolve themselves half-way 

 towards the compound eye into a plexus of filaments (optic nerves) 

 for its several divisions. Two separate antennal nerves, conjectured 

 by Straus Durcheim to be motory and sensory (d, d), are sent off on 

 each side below and in front of the optic nerves to the short, seven 



FIG. 3&L 



Brain and principal nerves of lulus. 



jointed antennae. On each side, also, but below the antennal nerves, 

 arise the two nerves (b), united together by an anastomosing branch, 

 which supply the mandibles. 



1092. The thick cssophageal chords (g) are continued from the 

 posterior and inferior angles of the brain ; and, though apparently 

 simple, consist essentially of two chords, which become separate at 

 the lower part of the pharynx ; the anterior chord girts the pharynx 

 by a transversely oval ring, formed by the confluence with its fellow ; 

 the posterior and normal columns converge, at an acute angle back- 

 wards, blend together, and expand into the commencement of the 

 abdominal nervous trunk ; thus enclosing the oesophagus by a second 

 and looser collar. 



1093. The stomato-gastric, or sympathetic nerves (/), which 

 arise from the posterior part of the brain, immediately form a third 

 slender ring (e) about the cssophagus, from the middle of the upper 

 part of which the trunk of the sympathetic system is continued a 

 short way back upon the stomach, when it divides ; the two divisions 

 diverge at an angle of 45, bend abruptly backwards, and run parallel 

 with each other along the dorso-lateral parts of the wide and straight 

 alimentary canal. 



1094. Two large nerves (h) are sent forwards from the beginning 

 of the thick sub-03sophageal or ventral chord (i), to supply the max- 



