94 



ANATOMY OF AN ARTHKOPOD. 



afresh to the body through the opening in front by a rhythmical 

 contraction of the walls of the tube. There are no blood-vessels 

 as in higher animals ; the blood is poured into the body cavity, 

 and there bathes the organs and comes in contact with the re- 

 spiratory tubes. An opaque- white 



A, J-' ' mass of fat, the /a^-SofZy, surrounds, 



Si IlU'A W-"^"' °''' ^s^'^v SO) the abdomen. 



s Im^^^^^ ' ■''""' ^^® digestive organs can be easily 



if!M5^^'^lk' ' °^ unravelled, so that each part is dis- 



Vc fflMiFTi-^- "'■>' tinctly visible. The alimentary tube 



^Ew M ' T '^ is short, and convoluted in the hinder 



^^ffitS^ Tn parts. The first portion is lodged in 



'^HB£:Jj|li,' "''^^ the head, and is called the buccal 



WiW^Ey ' cavity, into which open two glands, 



OTtBli'iWl °'^® ^'^ each side, the salivary glands 



^^rXg^p^. .. , . {Sg), by a single salivary duct iu a 



'^Srl^S* i\^^ median aperture. Then follows a 



1% /^^ ' narrow gullet or wsophagus (Oes), 



^^t^^^y- which gives rise to a thin- walled sac 



jf^ ^^^^—^ which is situated in the thorax and 



— iW- part of the abdomen, the crop (P). 



Fio. 34.— Digestive Oeqans of The crop is thin - Walled ; but the 



THE CocKEoACH. gucoeeding division, the gizzmd (G) 



Oes, CEsophagus ; Sd, salivary i_ i i i i i 



duct ; Sg, salivary glands ; p, or stomach, has liard musciuar 



proveutriculus ; G, gizzard ; H, ^^ ^ . . . , j i.i_ 



iiepatic caica ; Mc, Maipighian walis and contams SIX large teeth. 



tubes ; Li, large intestine ; Si, nii t . . , 



niesenteron ; jt, rectum ; M, anal J- hese alimentary parts are known 



gland; C&.j;, cerebral ganglia : S.q, ii j _* ? i - j j 



sub - cEsophageai ganglion ; n-.c, &s the stomatodcKiim, bemg formed 



nerve - collar ; Th, i to Ah.q Q i i. • • • i- -at. 



ganglia. ' by an anterior invagination m the 



embryo. The stomatodoeum has a 

 chitinous lining continuous with the chitinous cuticle of the 

 head. Following the gizzard will be observed a short thin 

 tube, which forms a connection between the original anterior 

 and posterior invaginations of the embryo. It is called the 

 mesenteron {Si). The hinder parts of the canal are composed 

 of the small and large intestines and rectum. The proximal 



