514 



SGIENGE. 



[N. S. Vol. VII. No. 172. 



"Without a fuller statement than that re- 

 cently given, it would be unfair to criticise 

 Professor Patten's hypothesis. No physi- 

 cist should criticise anything more than the 

 assumption that the length and angular re- 

 lations of a fibril determine the amount of 

 its response to a wave of light of a given 

 length and plane of vibration. To be valid 

 the assumption should imply that each 

 fibril has a definite rigidity in a definite 

 plane so as to respond to special transverse 

 vibrations. The subject scarcely offers a 

 field for mathematical examination, and 

 direct disproof is impossible. If this 

 hypothesis is destined to outlive its an- 

 nouncement it must be because it is found 

 to serve better than other hypotheses for 

 the explanation of such troublesome visual 

 phenomena as phosphenes, after-images 

 and simultaneous color-contrast. Even if> 

 it should stand this test the physicist will 

 probably be cautions about either attacking 

 or sustaining it. 



So far as the phenomena of physics are 

 linked with those of sensation, it is natural 

 that physicists should quite generally en- 

 tertain a high respect for the conclusions 

 reached by Helmholtz, an investigator who 

 as a physiologist took rank with the most 

 accomplished of his contemporaries, and 

 whose brilliant work in physics can be 

 judged by physicists more readily than that 

 in physiology. When his important work 

 on Physiological Optics was published, in 

 1866, the ' new psychology ' was yet unborn. 

 Even to-day it is not easy to assign a di- 

 viding line between psychology and the 

 physiology of brain and nervous system. 

 The hypothesis of color vision originated by 

 Young, and revived after a half century by 

 Maxwell and Helmholtz, has served a very 

 useful purpose as a working hypothesis for 

 physicists, and under present conditions 

 it bids fair to serve them yet for a number 

 of years in the same capacity. On such an 

 extra-physical subject as sensation the 



physicist has scarcely any choice but to ac- 

 cept the consensus of opinion among the 

 leaders in physiology and psychology. If 

 the latter are irreconcilably at variance 

 among themselves — and every new ' theory 

 of vision ' seems to emphasize this infer- 

 ence — the physicist must retain the working 

 hypothesis which has been already found 

 useful, however unsatisfactory it may be to 

 those who are at variance. It may be per- 

 fectly legitimate for him to recognize, and 

 even emphasize, what seems unproved in 

 his working hypothesis, and thus openly 

 profess his uncertainty. This cannot be 

 greater than the uncertainty with which he 

 would join some faction of the psycholo- 

 gists. If he wishes to test all the theories 

 of color vision now offered him he must 

 give up physics to a considerable extent 

 and study psychology enough to become an 

 investigator in this subject. 



Without attempting to refute any one 

 hypothesis of color vision, it may be suffi- 

 cient to say that there are now at least seven 

 of these presented as competitors for favor, 

 four out of the seven having been an- 

 nounced during the last half dozen years. 

 First is the Young-Helmholtz hypothesis ; 

 then comes that of Hering, which was its 

 only competitor until 1887, when Wundt 

 published his important paper entitled 

 ' Die Empfindung des Lichts und der 

 Farben.' In 1892 appeared Mrs. Frank- 

 lin's ' Eine neue Theorie der Lichtempfin- 

 dungen,' which was followed in 1893 by 

 Ebbinghaus's ' Theorie des Farbensehens.' 

 Still another competitor was brought for- 

 ward by Mcati in 1895, to be followed in 

 1897 by the new American competitor just 

 announced. The bewildered physicist is 

 already a fit subject for commiseration, and 

 apprehension about the future tends to. 

 make him yet more unhappy. He despair- 

 ingly beseeches the psychologists to agree 

 among themselves, but they will not agree ; 

 on the contrary, the prospect seems to be 



