80 



twenty and twenty-five trials three rata finished, at twenty- 

 three, twenty-four and twenty-four trials resj.eotively; the 

 average is twenty-three, and the third point on the curve in- 

 dicates that three rats finished at twenty-three trials. The 

 same procedure is followed in drawing the time and distance 

 curves except that they are necessarily more condensed. Three 

 rats required approximately four hundred seconds each in which 

 to learn the problem, (numbers 11, 15 and 24], and the first 

 point on the time curve indicates this fact. The fourth point 

 shows that six rats consumed from fifteen thousand to twenty 

 thousand seconds (average for the six seventeen thousand sec- 

 onds), in their total number of trials. The fifth point in 

 the distance curve is interpreted to mean that six rats cover- 

 ed between three hundred thousand and three hundred fifty thous- 

 and centimeters, (average for the six, one hundred seventy 

 thousand), in learning the maze. It might be well to notice 

 at this point that all of the curves appearing in this paper 

 are constructed on this same plan. 



The trial curve, (Pig. 3-A) for this group reaches the 

 apex at about thirty, which is the average number of trials 

 for this age . 



Two maxima appear in the time curve, (Pig. 3-B) at 

 eight hundred seconds, and at seventeen hundred seconds re- 

 spectively. A point intermediate between the two v.ould give 

 the tine average for the group, approximately thirteen hundred 

 seconds. 



The apex of the distance curve, (Pig. 3-C ) , is at three 

 hundred thousand centimeters, which is not far from the grouj, 



