SCOPE OF GENETICS 21 



which go far below the surface. Amazing 

 though they be, they are nevertheless true ; 

 for though our witness may prevaricate, she 

 cannot lie. Piecing these answers together, 

 getting one hint from this experiment, and 

 another from that, we begin little by little to 

 reconstruct what is going on in that hidden 

 world of gametes. As we proceed, like our 

 brethren in other sciences, we sometimes re- 

 ceive answers which seem inconsistent or even 

 contradictory But by degrees a sufficient 

 body of evidence can be attained to show 

 what is the rule and what the exception 

 My purpose today must be to speak 

 rather of the regular than of the irregular. 

 One clear exception I may mention. 

 Castle finds that in a cross between the 

 long-eared lop-rabbit and a short-eared 

 breed, ears of intermediate length are pro- 

 duced: and that these intermediates breed 

 approximately true. 



