38 



PIEBALD RATS AND SELECTION. 



Table 15. — Mean grade and number of offspring produced by parents of a particular grade in each 

 generation of the plus selection series, based on Tables 1-18. The grade of the parents is indicated 

 at the head of each column. In the body of the table is recorded the grade of the offspring {in light- 

 faced figures) and the number of offspring (in heavy-faced figures) . 



Table 16. — Classification of the offspring in generation 1 of the minus selection series. 



