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Elementary Biology. 



food down to a stomach, or store-chamber, where the food 

 is mixed with digestive secretions ; an intestine, or narrow 

 canal, where further digestive changes are effected, and 

 where the nutritive part of the food is chiefly absorbed into 

 the circulation ; and lastly a rectum where the effete or 

 useless portions are collected, and from which they are 

 periodically got rid of through the cloaca. 



FIG. 128. RANA TEMPORARIA. (Milnes Marshall.) 



Again, the secretions with which the food is mixed, and 

 which render it capable of being absorbed, are produced in 

 glands which are either minute and sunk in the wall of the 

 alimentary canal itself, or are large and distinct from it, but 

 opening into it by ducts at various points. These glands, 



