?ive Hundred Day Rata . 



Records on only ten rata h&ve been obtained in thi3 group, 

 six strains being represented by four malea and uix femalea who 

 began the problem when five hundred days old. These rata lixe 

 the 300-day animals were fed in the maze for ten days previous 

 to the commencement of the problem, and allowei to eat for from 

 six to eif^ht minutes at the clone of each days work on account 

 of their age. Little differeace in behavior was noted between 

 them and the three hundred day animals. 



CF i.2/n BE ^/s/m CP V^//^ BH %^-/n V.^ '^/t/^ EJ ''/"//^ Total 



10 3 4 



112 10 1 6 



All 1 1 3 1 5 1 10 



Too few rats have been used to make this group really com- 

 parable with the rest, but averages and totals are nevertheless 

 shown. Trials varied in number from eighteen to fifty-six, ab- 

 solute time from five and four tenths seconds to seventeen and 

 eight tenths seconds, total tine from one hundred and sixty-seven 

 minutes to eleven hundred and sixty-seven minutes, and total 

 distance from one hundred seventy-tv.o and eight tenths meters to 

 six hujidred forty-one and six tenths meters. 



Again there is no relation apparent between trials and time 

 or distance, and total time and total distance do not bear a pro- 

 portional relation to each other. (Table VI) The rat which 

 finished in the fewest trials (18} had next to the highest time 



