62 



The Form of Insects 



tube which stretches from the mouth, where food is 

 taken in, to the vent, situated at the extreme hinder 



end of the abdomen, 

 where waste-matters 

 are cast out of the 

 body. 



If a Cockroach's 

 body be opened, the 

 food-canai (fig. 43) 

 is seen to occupy a 

 central position lying 

 below the heart and 

 above the nerve- 

 cord. It is readily 

 divisible into various 

 regions. The mouth 

 leads into a narrow 

 gullet (oesophagus ) , 

 surrounded by the 

 nerve - ring of the 

 head, passing back- 

 wards through the 

 neck into the thorax, 

 where it gradually 

 swells out into the 

 large, pear - shaped 

 crop, which stretches 

 into the front part of 

 the abdomen. 



Crop. — The crop, 



as well as the gullet, 



,. f 1 r- 1 f r- 1 u c • .T has thin walls which 



!• IG. 43. — Food Canal of Cockroach. .c Spittle 



glands and reservoir ; c. crop (the gizzard below are COmpOSCd Ol 



it) ; coe. coecal tubes (below them the stomach) ! . i i 



k. kidney tubes ; i. intestine; r. rectum. Twice tliree layers an 



natural size. From Miall & Denny. Q^^gj. ^usCular layer 



consisting of striated fibres, arranged lengthwise and 



