Genetic Material and Mitosis 13 



WlLHELM LUDWIG JOHANNSEN 



(1861-1926). (From Genetics, 

 vol. 8, p. 1, 1923.) 



Spector, W. S. (Ed.), "Chromosome Numbers," in Handbook of Biological Data, Phila- 

 delphia: Saunders, 1956, pp. 92-96. 



Swanson. C. P., Cytology and Cytogenetics, Englewood Cliffs, N.J.: Prentice-Hall, 1957. 



Swanson, C. P.. The Cell, 2nd Ed., Englewood Cliffs, N.J.: Prentice-Hall, 1964. 



QUESTIONS FOR DISCUSSION 



1.1. Does the phenotype of one generation have any effect upon the genotype of the 

 next? Explain. 



1.2. Evaluate the thesis that the genotype is more important to organisms than is the 

 environment. 



1.3. Is the environment for two organisms ever identical? Explain. 



1.4. What is meant by an operational definition? 



1.5. Define the genetic factor. Have you given an operational or a nonoperational 

 definition? Explain. 



1.6. When the same similarities or differences in phenotype can be produced by either 

 the environment or the genotype, can one ever be sure which is the determining 

 factor? Explain. 



1.7. What evidence can you give to support the view that genetic material is trans- 

 mitted from parent to offspring? Do you think this evidence constitutes conclu- 

 sive proof of transmission? Explain. 



1.8. What conclusions can you reach regarding the genetic factor in Himalayan rabbits 

 and in Siamese cats? 



