LIFE PROCESSES IN ANIMALS 285 



18. Of what use to an animal is the nervous system ? 

 What are the principal parts of this system? 



19. How long do animals live? 



20. If possible, ascertain the average number of 

 years which man lives. 



21. How can you account for this low figure ? 



22. HOW T do one celled animals reproduce? 



23. What is an egg cell? A sperm cell? 



24. What is a fertilized egg? 



25. What is the function of the white arid the yolk 

 of a chicken's egg? 



