PRESENT PROBLEMS OF PHYSIOLOGY 433 



observed processes may all be due solely to the material structure 

 of the fertilized ovum acting in accordance with physico-chemical 

 laws, and that, therefore, our present methods of investigation 

 may eventually bring these phenomena within the limits of a scien- 

 tific explanation. The irreducible residuum recognized to-day, and 

 indeed admitted always by many of the physiologists who are 

 reckoned among the mechanists, is the psychical reaction, the phe- 

 nomenon of consciousness. However much we may come to know 

 of the physico-chemical processes that give rise to this reaction, it 

 has been asserted by most of the scientific authorities of our time 

 that the psychical side itself is beyond the possible application of 

 the methods of physics and chemistry, a conclusion that, as it seems 

 to me, is tantamount to the admission of the existence of a non- 

 material reality. The study of consciousness has therefore been 

 eliminated from the subject of physiology on the ground that the 

 methods of our science are inapplicable. I fully agree, however, with 

 the timely and courageous statement of Minot * that "Conscious- 

 ness ought to be regarded as a biological phenomenon, which the 

 biologist ought to investigate in order to increase the number of 

 verifiable data concerning it." If for the present this task is con- 

 fided to the workers in the independent science of psychology, the 

 only successful methods that they can employ are those of obser- 

 vation and experiment, and eventually the latter mode of investi- 

 gation must become the more important, and the subject must be 

 recognized as destined to come within the province of experimental 

 physiology. To Minot the most important work at present is to 

 be accomplished by an extension of the comparative method to the 

 psychological study of all forms of life, but to the physiologist it 

 would seem that a no less promising although technically more 

 difficult field will be found in neuro-pathology, which holds out 

 hopes that definite variations in the psychical reaction may be con- 

 nected with distinct alterations in the structure and properties of 

 the material substratum. One can scarcely doubt that the combined 

 labors of the psychologist, biologist, physiologist, and pathologist 

 will eventually accumulate many verifiable data concerning con- 

 sciousness. We are not able at present, it is true, to form any con- 

 ception of the nature of the relation between the subjective and the 

 objective, but new facts may alter wonderfully our insight into this 

 mystery, and it is the clear duty of physiology to participate in the 

 work of accumulating all possible data bearing upon this relation. 

 The introspective method alone is insufficient, and we have no 

 alternative but to trust hopefully in the less pretentious method of 

 scientific observation and experiment. We may believe that in this 



1 Minot, Presidential Address, American Association for the Advancement of 

 Science, Pittsburgh Meeting, Science, xvi, p. 1, 1902. 



