The Visible Basis of Heredity 85 



questions 



1 . Have you seen cells under the microscope ? You 

 can see them with the naked eye in some vegetable 

 tissues, when they are much swollen with sap, as in the 

 pulp of watermelon, or in the coarse tissue of the 

 water-lily leaf or elder pith. Will some member of 

 the class supply some such material ? Such cells have 

 largely lost their living protoplasm. 



2. In cell division what is the customary behavior 

 of the chromosomes ? 



3. Why is a reduction in the number of chromo- 

 somes necessary when the plant or animal reproduces 

 by eggs ? 



4. What primarily determines the sex of an 

 animal ? 



5. What is the evidence against birthmarks? 



6. Why does the fruit-grower propagate by cuttings 

 rather than by seed ? 



