INSECTS 



279 



from the perivisceral cavity into the pericardial. The peri- 

 visceral and pericardial spaces contain a white tissue known 

 as the fatty body, which appears, among other functions, 

 to play some part in the formation of uric acid. 



sat r. 



v.'n.c. . 



snalg. 



Mp.t. 



col.g. '" ' can. 



Fig. 183. — A female cockroach, dissected from above. — From Shipley 

 and MacBride. 



at., Antenna; can., anal cerci ; cer.g. cerebral ganglia; en., colon; col.g., col- 

 leterial gland ; cr., crop ; eye ; gen.p., genital pouch ; giz., gizzard ; h., head ; 

 hp.c, hepatic CKCa ; Ibr., labrum ; m.g., mesenteron ; Mp.t., Malpighian tubes ; 

 od., oviduct ; ov., ovary ; rm., rectum ; sal.g., salivary glands ; sal.r., salivary 

 receptacle ; sp., spermathecae ; v.11., visceral nerves ; v.n.c, ventral nerve cord. 



The nervous system is on the same general plan as that 

 of the crayfish. It comprises a pair of supra- 

 s er t"m S nd oesophageal ganglia, which receive optic and 

 sense Organs, antennary nerves, a pair of short, wide cir- 

 cumcesophageal commissures, a subcesophageal 

 ganglion, and a double ventral cord with a ganglion in 

 each of the first nine segments behind the head. The 



