382 



C. H. TURNER. 



Szymanski, in his study of larval male cockroaches, arranged 

 them in three classes : those that learn rapidly and fatigue slowly, 

 those that learn rapidly and fatigue rapidly, those that learn 

 slowly and fatigue rapidly. Arbitrarily I can classify the roaches 

 studied by me in the same manner; but, there are no sharp 

 demarcating lines. It is also possible to divide roaches into 



10 IT 3.0 If 30 3f~ 



B 



t-f 



r 10 



3f t-o 



C 



D 



FIG. 4. Reaction curves of four larval females one half of an inch long; a repre- 

 sents refusals to enter the dark chamber, b represents entrances into the dark 

 chamber. 



groups based upon their ability to learn and to retain what they 

 have acquired. Some roaches are quick to learn and retain well 

 what they have acquired (Table I., numbers 7 and 8; Table II., 

 numbers 15 and 20; Table III., number 2; Table IV., number 

 41); some are quick to learn but not very retentive (Table IV., 

 number 13); some are slow to learn, but retain well what they 



