42 

 has "been shown .by the irregularity of the curves and 



also in the number of the trials. 



As a result the question arises as to the compara- 

 tive value of a saving of days or a saving of trials. 

 This can be answered by considering the amount of energy 

 consumed and the span of life of the rat. If several 

 trials are given and energy is too freely used, one trial 

 is the most economical; but, if this is not the case and 

 no harmful results are evident, then several trials daily 

 are the most advantageous in the number of days y and the 

 number of days is of some importance when the short life 

 of the rat is considered. If, in the life-time of the rat, 

 several problems are to be learned, it is almost necessary 

 to give several trials daily. This has additional weight 

 when it is considered that the youth of the rat t when 

 learning is best accomplished, is very short. The conclu- 

 sion can be reached that, if the life of the rat is to 

 be a strenuous one, several trials are more profitable, 



