26 



FEEDING FARM ANIMALS 



smaller, the real digestive act, the absorption of the 

 nutriment in the food by the blood, takes place. 

 Up to this point, although the fluids have been at 

 work, there has been little if any active absorption 

 into the system. The food up to now is in 

 a sense outside the body; and there is no entrance 

 or opening for it to get into the body, save through 

 the cells that line this part of the digestive tract. 

 In a way similar to that by which soluble plant food 



is admitted into the 

 plant roots through 

 the cell walls, so is 

 the digested food, 

 after it has been 

 broken up and made 

 soluble, absorbed 

 through the cell 

 walls of the intes- 

 tines into the blood 

 system of the ani- 

 mal. 



From Intestines to 

 food 

 it is ad- 

 mitted either to the 

 capillaries of the blood or to the lymphatic system. 

 If collected by the capillaries the absorbed food 

 is carried to the portal vein, thence to the liver 

 and finally to the heart, where it is poured with 

 the blue blood as it is brought in from all parts 

 of the body. At this point the blood contains 



a 



"a m v I 



VILLI CELLS 



Section of intestine showing villi. The Blood 



parts are as follows: a, arteries; b, villi; 

 c, villi cut open to show lacteal (/), and jg 

 blood tubes; d, glands; m, muscle; v, 

 veins; and w, wall of intestine. 



