July 4, 1903.] 



SCIENCE. 



9 



thought into which the data are trans- 

 mitted. In pleading therefore for an in- 

 creased observational study of conscious- 

 ness we plead, not merely for science, but 

 equally for philosophy. The scientific 

 progress must come first. Hence we urge 

 the advantage of investigating conscious- 

 ness in its immediate revelations which are 

 accessible now. Let us give up the ineffec- 

 tual struggle to discover the essential na- 

 ture of consciousness until we can renew 

 it with much larger resources of knowl- 

 edge. 



The psychologists ought now to apply 

 the comparative method on a grand scale. 

 They are just beginning to use it. Years 

 of patient labor must pass by, biit the re- 

 ward will be very great. The psychic life 

 of animals must be minutely observed, the 

 conditions of observation carefully regu- 

 lated and the results recorded item by item. 

 The time has passed by for making general- 

 izations on the basis of our common, vague 

 and often inexact notions concerning the 

 habits of animals. Exact experimental 

 evidence will furnish a rich crop of psy- 

 chological discovery. Scientific psychol- 

 ogy is the most backward in its develop- 

 ment of all the great divisions of biology. 

 It needs, however, little courage to proph- 

 esy that it will bring forth results of mo- 

 mentous importance to mankind. After 

 data have been gathered, generalization 

 will follow which, it may be hoped, will 

 lead us on to the understanding of even 

 consciousness itself. 



The teleologieal impress is stamped on 

 all life. Vital functions have a purpose. 

 The purpose is always the maintenance of 

 the individi;al or of the race in its environ- 

 ment. The entire evolution of plants and 

 animals is essentially the evolution of the 

 means of adjustment of the organism to 

 external conditions. According to the 

 views I have-laid before you, consciousness 

 is a conspicuous, a commanding, factor 



of adjustment in animals. Its superiority 

 is so great that it has been, so to speak, 

 eagerly seized upon by natural selection 

 and provided with constantly improved 

 instruments to work with. A concrete 

 illustration will render the conception 

 clearer. In the lowest animals, the 

 coelenterates, in which we can recognize 

 sense organs, the structure of them is very 

 simple, and they serve as organs of touch 

 and of chemical sensation resembling taste. 

 In certain jelly fishes we find added special 

 organs of orientation and pigmented spots 

 for the perception of light. In worms we 

 have true eyes and vision. In vertebrates 

 we encounter true sense of smell. Fishes 

 cannot hear, but in the higher vertebrates, 

 that is from the amphibians up, there are 

 true auditory organs. In short, both the 

 senses once evolved are improved and also 

 new senses are added. It is perfectly con- 

 ceivable that there should be yet other 

 senses, radically different from any we 

 know. Another illustration, and equally 

 forcible, of the evolution of aids to con- 

 sciousness might be drawn from the com- 

 parative history of the motor systems, 

 passing from the simple contractile thread 

 to the striated muscle fiber, from the prim- 

 itive diffuse musculature of a hydroid to 

 the highly specialized and correlated mus- 

 cles of a mammal. 



It is interesting to consider the evolution 

 of adjustment to external reality in its 

 broadest features. In the lowest animals 

 the range of the possible adjustment is 

 very limited. In them not only is the 

 variety of possible actions small, but they 

 cover also a small period of time. In 

 animals which have acquired a higher or- 

 ganization the adjustments are more com- 

 plex, both because the reactions are more 

 varied and because they cover a longer 

 period of time. Thus the jelly fish de- 

 pends upon such food as happens to come 

 within its reach, seizing from moment to 



