IN RATS AND GUINEA-PIGS. 



Individuals 



Grade 4.5 



34.5 4-4.5 54.5 6*5 74.5 



FIG. 3. Variation in extent of the back-stripe in lots A to F of hooded rats, showing the effects 

 breeding with rats of Irish pattern. The positions of the means are shown by vertical lines 



of cross- 



