384 PECKHAM. [Vol. i. 



tionary measures of the scientific method Hes just in the neu- 

 traHzing of the influence of the observer's subjectivity. The 

 subjective element cannot, of course, be ehminated ; but the 

 observer should keep facts and inferences separate, and should, 

 in addition, state the particular action, among the many, which 

 is the external sign of the mental state which he believes to be 

 proved by the experiment. Lange's words on the subject are 

 worthy of immortal memory: — 



" Where external observation shows us primarily only move- 

 ments, gestures, and actions, the interpretation of which is liable 

 to error, we may, nevertheless, carry out a comparatively very 

 exact procedure, since we can easily subject the animal to ex- 

 periments, and put it into positions which admit of the most 

 accurate observation of each fresh emotion, and the repetition 

 or suspension, as we will, of each stimulus to a psychical activity. 

 Thus is secured that fundamental condition of all exactness ; 

 not, indeed, that error is absolutely avoided, but certainly that 

 it can be rendered harmless by method. An exactly described 

 procedure with an exactly described animal can always be re- 

 peated, by which means our interpretation, if it is due to variable 

 bye-conditions, is at once corrected, and at all events thoroughly 

 cleared from the influence of personal preconceptions, which 

 have so great a share in so-called self-observation."^ 



We have felt that it might properly be demanded of us that 

 we give the generic and specific names of every spider experi- 

 mented upon, and also that we so describe our methods that 

 the experiments can be repeated by any one wh.o desires to test 

 the validity of our conclusions. 



Our rule has been not only to repeat an experiment many 

 times, but to repeat it under as many different conditions as 

 possible. The histologist often finds it necessary to adopt com- 

 plicated and tiresome methods in order to demonstrate a single 

 fact. So, also, we have found that to learn anything of the 

 mental processes of spiders the way is long and beset with 

 difficulties. To use the words of Ribot: "Many of these inves- 

 tigations, we shall see, pertain to very modest questions, and it 

 is probable that the partisans of the old psychology will find 

 the work too great for results so small. But those who give 

 allegiance to the methods of the positive sciences will not com- 

 ' History of Alaterialism, Vol. III., p. 178. 



