306 AN INTRODUCTION TO ZOOLOGY 



plastic individual deliberations or adaptations " (240, p. 36). 

 Other authorities consider the power to learn by individual 

 experience, for example, the habit-forming in the crayfish (p. 223), 

 as evidence of mind. And still others deny the presence of mind, 

 attributing every act to chemicophysical processes. 



It certainly is true that no one knows whether animals are 

 conscious or not. Our evidence is all gained by inferences from 

 behavior. The conditions under which the facts of behavior ai 

 obtained are of great importance. Anecdotes are of little value, 

 since the observer is not scientifically trained, and, wishing to tell 

 a good story, tends to exaggerate the apparent intelligence of 

 animal. The modern method is that of carrying out definite 

 experiments, the habits of the species and past experiences of tl 

 individuals being known. The conclusion is then based on 

 least complex interpretation that will account for the facts of 

 behavior observed. We can, however, only interpret behavioi 

 on the analogy of human experience, the tendency being to 

 cribe human traits to animals. 



Learning by experience, a process considered by many indica- 

 tive of intelligence, is one of the criteria of the presence of mind; 

 but the modifiability of the behavior must be rapid, or tim( 

 enough for a change in body structure may elapse. Structure 

 is a distinct help in inferring mind, since animals with a nerv- 

 ous system similar to that of Man must be affected by external 

 stimuli in a similar way. 



" We know not where consciousness begins in the animal 

 world. We know where it surely resides in ourselves; 

 know where it exists beyond a reasonable doubt in the 

 animals of structure resembling ours which rapidly adapt them- 

 selves to the lessons of experience. Beyond this point, for all 

 we know, it may exist in simpler and simpler forms until we reach 

 the very lowest of living beings " (276, p. 36). 



