STRUCTURE OF THE HOUSE-FLY 47 



.thorax, where are the entrances to two long capacious 

 chambers, of which the upper one is the true stomach 

 and the lower one a store pouch, which latter may be 

 likened to the honey bag of the bee. The fly habitually 

 regurgitates liquid food stored in this pouch, and, 

 somewhat after the manner of the cow chewing the 

 cud, passes the same back into the true stomach, 

 whence it proceeds onwards through the digestive track. 



The abdomen holds all the other ordinary internal or- 

 gans including that which may be called the heart, and 

 which lies above the stomach ; it consists of a long 

 muscular tubular vessel with four contractile chambers. 



Although the organ called the brain is located in the 

 head, and although that called the heart is in the 

 abdomen, yet some sense of control over bodily motions 

 curiously exists separately in the ganglions of different 

 parts of the body. This fact seems to make it possible 

 for one extremity of the body to continue performing 

 a pleasurable action (say, the head drinking honey) 

 after the other extremity has endured a painful catas- 

 trophe (say, amputation of the abdomen). However, 

 it may be fairly surmised that no creatures of a lower 

 grade than warm-blooded vertebrate animals feel 

 pleasure and pain in any way at least after the manner 

 of mankind. 



The most vital part of the fly is not the head but the 

 thorax. A severe squeeze on the thorax will effectually 

 paralyse and kill the creature. Muscular movements 

 of different parts of the fly's body, which continue after 

 severance or other fatal injury, cannot be regarded as 

 visible proof of a slow death and prolonged sensibility. 



Possessed of six legs, each with nine joints, the fly 



