222 FEEDING 



lungs, where it gives off the poisonous carbon dioxide and 

 takes in oxygen. After being purified in the lungs, the 

 blood is brought back to the left side of the heart from which 

 it is once more pumped to all parts of the body. So it 

 nourishes and builds up the tissues. From this brief 

 discussion of feed consumption and assimilation may be 

 noted the close analogy between the bird and the machine, 

 which, if borne in mind and followed, will lead to a better 

 knowledge of the requirements of individual fowls for 

 different types of production. 



LABORATORY EXERCISES 



Exercise No. 58.— Osmosis a Process of Assimilation. — 

 Fill a small paper bag full of a strong salt solution. Care- 

 fully tie the top and place the bag in a pail of clear, fresh 

 water. After remaining in the water for ten minutes care- 

 fully remove and taste of the water in the pail. How did 

 the salt get into the fresh water? 



Exercise No. 59. — A Study of the Digestive Tract. — Dis- 

 sect a mature fowl. Carefully remove the entire digestive 

 tract, including liver and pancreas, without rupturing any 

 part. Lay the organs out carefully on a table or drawing 

 board in such a way that the course of feed through same 

 can be described. The function of the organs and the loca- 

 tion may be discussed very clearly in this way. 



THOUGHT QUESTIONS 



1. In what can a bird be likened to a machine? 



2. Define digestion. 



3. Where does digestion take place? 



4. Define assimilation. 



5. Where does assimilation take place? 



6. Define nutrition. 



7. What is a nutrient? 



8. Of what is the digestive tract made up? 



9. What are the four different types of work performed by the diges- 



tive tract? 



10. Describe the mouth parts of land and water birds. 



11. What is the function of the beak? 



