GENERAL ANIMAL FUNCTIONS. 79 



tion takes place by the action of the juices secreted by 

 the gland cells in the wall of the tract. The physical 

 digestion takes place chiefly in the mouth and stomach; 

 the chemical in the stomach and intestines. Absorption 

 takes place in the stomach and intestines, chiefly in the 

 latter. Usually the surface of the intestine is much in- 

 creased by folds and coils, so that greater^ absorption is 

 secured. 



FIG. 9. Stenostoma. In this worm the digestive tract (dt.) is a blind sac. st, 

 point where the ectodermal mouth joins the entodermal gut ; c, cilia; g, ganglion (brain) ; 

 g', a new brain, forming for the new worm that is being produced by fission; o, mouth; 

 o' , mouth of new worm; w, excretory system. 



Questions on the Figure. Compare this digestive tract with those 

 of Figs. 5 and 58. What does proctodceum mean? How much 

 of this is proctodaeum? How would food be handled by a tract like 

 this? What would happen to it after digestion? Enumerate the 

 evidences that this worm is dividing. 



Glands are very common in connection with the intes- 

 tine. These may be simple, with only one or a few cells, 

 or they may become very much branched and enlarged. 

 Illustrations of the latter kind may be seen in the liver or 

 pancreas of man and the higher animals. Seek figures of 

 these in the reference texts. 



Figs. 9 and 63 w r ill show some of the main regions 



