THE ABSORPTIVE SYSTEM. 81 



two processes just referred to, and a careful stu^y 

 of this plate will enable us to understand their rela- 

 tion to and connection with each other. How, then, 

 does the digested food get into the circulation? 

 What provision is made for transferring it from the 

 alimentary canal to these blood-vessels? To answer 

 these questions, we must first study how food is 



absorbed. 



The food in its liquid form must in the 



Absorption. 



first place be removed from the stom- 

 ach and the intestinal tube. This is accomplished 

 by a process called absorption. This work may be 

 more easily comprehended by first referring to a 

 similar process constantly going on in vegetable 

 growths. Planted in good soil and supplied with 

 water, a plant will send out its small rootlets, whose 

 little mouths will drink in (absorb] mineral sub- 

 stances from the soil dissolved by the water. This 

 liquid plant-food is carried by the sap (vegetable- 

 blood) up the trunk or stem to nourish the parts of 

 the plant. There is a similar provision for taking 

 up the liquid food from the alimentary canal. There 

 are little rootlets provided for this work whose action 

 resembles that of the root-fibers of the plant. 



The inner wall or coating of the small 

 vnii 8tinal intestines has a velvety or plush-like 



appearance. This is due to the myri- 

 ads of little hair-like projections, which hang down 

 from the inner walls and point toward the center of 

 the tube. These small cones or fingers are called mill. 



