The Mind of the Simplest Animals 51 



absence of this kind of material in the possible mental pro- 

 cesses of Amoeba. In the first place, such a lack profoundly 

 affects the character of the experiences which the animal 

 might be supposed to receive through external stimulation. 

 If we call the possible conscious effect of a mechanical stimu- 

 lus upon the Amoeba a touch sensation, the term suggests, 

 naturally, such sensations as we ourselves experience them. 

 In normal human beings touch sensations are accompanied 

 by visual suggestions, more or less clear, of course, according 

 to the visualizing powers of the individual, but always pres- 

 ent in some degree. Fancy, for example, one of us enter- 

 ing a room in the dark and groping about among the furni- 

 ture. How constantly visual associations are brought into 

 play ! Not once is a mere touch impression apprehended 

 without being translated into visual terms ; the forms and 

 positions of the articles encountered are thought of imme- 

 diately as they would appear if the room were lighted. 

 The difficulty we have in thinking of a touch sensation with 

 no visual associations illustrates the difference between our 

 sense experience and that of an animal incapable of recalling 

 images of past sensations. 



It is equally obvious that in the absence of memory ideas, 

 not only must the Amoeba lack processes of imagination and 

 reasoning, but there can be nothing like the continuous self- 

 consciousness of a human being, the " sense" of personal 

 identity, which depends upon the power to revive past 

 experiences. It is even possible that the "stream of 

 consciousness" for an Amoeba may not be a continuous 

 stream at all. Since its sensitiveness to changes in its 

 environment is less developed than that of a human being, 

 and there are no trains of ideas to fill up possible intervals 

 between the occurrences of outside stimulation, the 

 Amoeba's conscious experience may be rather a series of 



