i8o A GUIDE FOR THE STUDY OF ANIMALS 



9. How are the young cared for in the following cases : 

 crayfish, cyclops, pipefish, Surinam toad ? 



Summary. 



1. What general methods are there for protecting the 

 young ? 



2. What various devices for assuring plenty of food for 

 the developing animal ? 



3. What is the relation between the care given the young 

 and the number of eggs produced ? 



D. Adaptations for the Preservation of the Species 

 Review Questions and Library Exercise 



1. Show how the sexual method of reproduction tends 

 to produce variations. 



2. What is meant by the term heredity f 



3. What are chromosomes ? What do some zoologists 

 believe to be the relation between these chromosomes and 

 heredity ? 



4. What are dominant and recessive characters ? What 

 is me^nt by " Mendel law of heredity " ? 



5. What is meant by the term parthenogenesis f What 

 are some of its advantages and under what conditions does 

 it take place ? Name some animal in which partheno- 

 genesis commonly takes place. 



6. What is sex dimorphism 1 Give some examples. 



7. What were the experiments of Professor Loeb and 

 others in connection with artificially fertilized eggs 1 



8. How do eggs vary as to the kind of shell, amount of 

 food, size, etc. .' What is the effect of the amount of food 

 upon the rate of development ? On the stage of develop- 

 ment at which the egg is hatched .■■ 



