364 



BIOLOGY FOR BEGINNERS 



In the simpler animals the digestive canal may be lacking 

 (protozoa), or almost straight and uniform in size (worms), but in 



Salivary &onef 



Vermiform typemfa. 



FIG. 114. Diagram of the alimentary canal. Modified from 

 Landon's, see Kellogg. 



the higher animals and man it is much coiled to provide greater 

 surface for secretion and absorption, and also varies much in 



