PHYSIOLOGY OF INSECTS. 145 



548. The stomach is double (ventriculus du- 

 plex] when it is divided into two distinct portions, 

 one preceding the other : in this instance the 

 anterior portion appears the principal organ of 

 digestion, and in form, as well as office, frequently 

 appears to resemble the gizzard of birds ; the 

 posterior portion corresponds with the stomach in 

 its usual simple form. 



549. The stomach is triple (ventriculus triplex) 

 when it possesses three separate divisions follow- 

 ing each longitudinally it sometimes, but rarely, 

 has four or more of these divisions. 



550. The stomach is compound (ventriculus 

 compositus) when it throws off two or more minor 

 stomachs (cceca\ resembling little purses, at or 

 near its union with the gullet; these are parti- 

 cularly observable in the voracious herbivorous 

 insects, which have the anterior portion of the 

 stomach in the form of a gizzard. 



551. The stomach varies also in the character 

 of its interior surface ; it is sometimes perfectly 

 smooth, and sometimes covered with a pilosity 

 more or less shaggy ; this pilosity has been said 

 to consist of minute tubular processes, which 

 secrete the fluid for digestion. 



552. The stomach, at its posterior extremity, 

 unites with the intestines ; these consist of two 

 portions, the small intestines (intestina parva), 

 and the terminal intestine (rectum). 



553. The whole of the alimentary canal, from 



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