318 THE PRINCIPLES OF AGRICULTURE 



extra time should be given to it. The reader 

 will do well to study it until he feels a sense of 

 mastery of the subject as here presented. 



What is a cell? Why does this discussion begin with the cell? 

 Discuss single-celled animals, as in paragraphs 3.')6-359. Do these 

 lowly animals have distinct organs? What is meant by "many- 

 celled animals?" What are the offices of individual cells in these 

 many-celled animals, as compared with tiiat of single-celled 

 animals? What is meant by the "process of nutiition?" By the 

 "nervous processes?" By the "processes of secretion" (36:ia)? 

 What are glands (3636), and what are some of their offices? 

 What are the offices of the corpuscles of the blood? With what 

 may these corpuscles be compared? What is the lymph and tlie 

 lymphatic system (365, 365a)? What is meant by a sjiecialized and 

 a generalized organ or organism (360rt)? 



What are the kinds of food as outlined in 367? What are 

 herbivorous animals? Carnivorous? How do the digestive organs 

 of the herbivorous animals differ from others? Compare the 

 digestive apparatus of tlie horse with that of the ox. How does 

 artificial care and selection modify the size of the digestive orgnns? 

 What must all foods contain in order to be of use to the animal? 

 Name nitrogenous foods. Name non-nitrogeneus foods. Wliat 

 is the special office of the latter? Are the non- nitrogenous foods 

 ever formed from the nitrogenous? How? What is meant by fat 

 (371rt)? What are the mineral salts? What is the constitution of 

 ideal food? What is meant by a well-balanced ration? Can a 

 definite mathematical ration be constructed that will be of equal 

 value for all animals? Explain. 



What is digestion? What is the alimentary canal? What are 

 the digestive secretions? Discuss saliva. What is the active 

 principle of saliva, and what is its office? What are ttie offices 

 of the various stomachs in ruminating animals? Wh;it is the 

 office of the chewing of the cud? How do the salivary glands 

 differ between youth and age? What relation has this to the kind 

 of food that an animal should have? What are the three digestive 

 principles produced by the stomach? Describe them. What is 



