QUESTIONS AND SUGGESTIONS 317 



These combine according to the law of chance. Combinations of 

 a pair of characters follow a definite proportion. 



Problem. How may the law of chance be demonstrated f 



I. Put in a jar one hundred black beans and one hundred white beans of 

 the same size. Mix the beans thoroughly. Without looking, take out two 

 beans at a time. 



A. Score the number of times two black beans, two white beans, and 

 one black and one white bean are taken out. 



B. At least one hundred pairs should be taken out before the scores 

 are summarized. 



C. State the proportion of two black to a combination of one white 

 and one black, and to two white. 



II. Toss two coins at least one hundred times before totaling your scores. 



A. Score the number of times two tails appear. 



B. Score the number of times two heads appear. 



C. Score the number of times one tail and one head appear. 



D. State the proportion of two heads to a combination of one head 

 and one tail, and to two tails. 



III. When it is pm^ely chance that controls the meeting of members of a 

 pair of characters, the proportion resembles that obtained with the beans and 

 coins. In order to get a proportion, the experiment should be carried on a large 

 number of times. 



Questions and Suggestions 



1. In what structures of germ cells are characters of organisms 

 located ? 



2. What is meant by heredity ? 



3. What effect has environment on development ? Give examples. 



4. What effect has ancestry on development ? Give examples. 



5. What effect has environment on ancestral traits ? 



6. Account for differences among offspring. 



7. How can the best offspring be obtained ? 



8. Discuss the law of chance. Describe an experiment to illustrate 

 it. 



9. How does the law of chance operate in the fertilization of an 

 egg by sperm? 



