212 'Journal of Comparative Neurology and Psychology. 



reach tbe very lowest of living beings. * * * No one can prove the absence 

 of consciousness in even the simplest forms of living beings. It is therefore 

 perfectly allowable to speculate as to what may be the nature of such con- 

 sciousness, provided that the primitive organisms concerned possess it." 

 She does not present the arguments which may be advanced for and against 

 the ascription of mental processes to the lower animals ; nor does she indicate 

 how probable or how plausible is her assumption that the lower animals 

 possess a consciousness. This may or may not be a serious omission, — prob- 

 ably many readers who have followed the discussions will agree that it it 

 not. But it does seem paradoxical enough that an author should devote 

 whole chapters to the description of something which, in the opinion of many 

 reputable scientists, does not exist ; and whose existence the author herself 

 is not willing to vouch for. 



An examination of the motor reactions of ameba and Paramecium is believed 

 to warrant the inference that the hypothetical protoizoan mind differs from 

 tbe human mind in certain essential and clearly definable features. The 

 mental stock-in-trade of the protozoon probably amounts to not more than 

 three or four qualitatively different sensations; there is an utter absence 

 of mental imagery (or revived sensations), and of anything correlate with 

 attention. (This inference, however, does not seem to be justified, in the 

 case of stentor, by Jennings' observations.) The mental life of the protozoa 

 cannot therefore be a continuous "stream of consciousness," but only a succes- 

 sion of discrete and isolated experiences of the most primitive sort. From 

 this humble beginning of mind, the author sketches in broad outline the 

 developing consciousness through the entire animal series. "The reactions of 

 animals to stimulation show, as we review the various animal forms from 

 the lowest to the highest, increasing adaptation to the qualitative differences 

 and to the spatial characteristics of the stimuli acting upon them. It is 

 therefore possible to suppose that the animal mind shows increasing variety 

 in its sensation contents, and increasing complexity in its spatial (and other) 

 perceptions. But besides this advance in the methods of responding to present 

 stimulation, the higher animals show in a growing degree the influence of 

 past stimulation." 



The author presents a detailed description of this increasing complexity 

 in animal response to stimulation. Three chaptei^ on sensory discrimina- 

 tion trace the development of sensory equipment (pp. 58-147). This is 

 followed by a discussion of spatially determined reactions and space percep- 

 tion (pp. 148-204). Here are considered the question of the adaptation of 

 animal reactions to the spatial relations of stimuli (light, gravitation, and 

 the like), and the question of animal perception of space. It is inferred that 

 orientation in the lower animals is probably due to an experience of impleas- 

 antness or uneasiness, — and that no spatial perception need be assumed to 

 account for the reaction. But certain responses to genuine visual stimuli (/. e., 

 where eyes are present) may be due to a consciousness of spatial relations. 



Chapters on "The Modifications of Conscious Pi'ocesses by Individual Ex- 

 perience" (pp. 20,5-209) describe the various labyrinth and puzzle-box exjteri- 

 ments, and discuss the elimination of useless movements in the acquisition 



