68 



HELEN B. HUBBERT 



In the tables, cases which undoubtedly show uniform pro- 

 gressive elimination, i.e., a 5-4-3-2 order, are doubly starred (**). 

 Cases which might possibly be considered progressive are singly 

 starred (*). Cases clearly not progressive are unmarked. 



TABLE I 

 Group A— 25 Days 



2 cases (**) uniformly progressive or 10%, vs. 90% not progressive. 

 9 cases where IV and V are eliminated before II and III, or 43%. 



DISCUSSION OF THE TABLES 

 Group A— 21 Rats 



These rats began the problem when twenty-five days old. 



Two of the twenty-one showed uniform progressive elimina- 

 tion, i.e., alley V was eliminated first, alley IV second, alley 

 III third and alley II fourth and last. We find then two cases 

 of uniform progression and nineteen cases clearly not uniformly 



