146 Journal of Comparative Neurology and Psychology. 



impulses which we think it is feeHng. In other words we must 

 use every means to ascertain the mental factors of the situation 

 before offering any interpretation of the meaning of the behav- 

 ior, or using the observed behavior to strengthen any particular 

 theory of psychic functional relations We cannot hope for ab- 

 solute certainty of the processes in other minds by any known 

 method, and the certainty is less the further we recede from our- 

 selves. But the careful student of the habits of the animal in 

 its natural condition, by exercising care to have the animal in 

 as nearly natural conditions as the experimental necessities ad- 

 mit of, and by being careful to isolate the experimental condi- 

 tions for the animal, will be able to interpret the movements 

 and incipient movements in mental terms and thus have a close 

 approximation to accurac)' in grading the intelligence of the an- 

 imal as shown in the particular situation. Accurate and detail- 

 ed knowledge of the natural life of the animal, it cannot be in- 

 sisted too strongly, is of the highest importance both for the 

 proper planning of experiments and for the interpretation of the 

 results. 



If under these conditions it can be shown that an animal 

 now has a grade of intelligence sufficiently high to serve as the 

 guide in shaping any and all of the instinctive modes of behav- 

 ior with which it is equipped, it has not been shown thereby, 

 of course, that intelligence was the means of its development. 

 The development of mind may have brought fourth this grade 

 of intelligence at a later stage in the race history than that at 

 which the instincts took their rise. In this case the results 

 would be merely negative. If, though, it can be shown that a 

 given animal has, as its mental equipment, an intelligence too 

 low to deal with a situation as complex as that dealt with by 

 the instinct, the inference is then clearthatthe instinct has come 

 by some other way than by intelligence. For our major prem- 

 ise, as before, is that intelligence as a whole never retrogrades, 

 but when released through automatization proceeds to greater 

 complexity and higher organization through dealing with more 

 complex situations. This case would presuppose a retrograd- 

 ing and would therefore be impossible. And so it was not con- 



