Maech 27, 1896.] 



SCIENCE. 



479 



question for him, therefore, is to choose between 

 authorities. 



No scientific man who has lived during the 

 nineteenth century has been more successful 

 in widelj' different fields than Helmholtz. Dur- 

 ing the last dozen years the words physicist 

 and electrician have become differentiated ; but 

 both were applicable to him as a distinguished 

 representative. As a mathematician he had 

 few equals. All physicists regarded him as an 

 exceptionally strong physiologist. Whether 

 their view is shared by the psychologists it 

 would perhaps not be proper for a physicist to 

 say. While the domain of the physicist is now 

 fairly well differentiated from that of the psy- 

 chologist, it is not yet possible to separate the 

 psychologist from the physiologist. If the physi- 

 cist has been too ready to accept Helmholtz' s 

 view on a purely psychological topic, he is to 

 some extent excusable in view of the high po- 

 sition attained by Helmholtz as an investigator 

 in subjects about which the physicist is by 

 special training capable of forming an opinion. 

 No one will maintain that Helmholtz was in- 

 fallible ; but the aggregate of demonstrated 

 mistakes made by him was so small in propor- 

 tion to the number of important discoveries 

 accomplished that his record may be safely 

 compared with that of any living psychologist. 



Upon what experiments, either crucial or 

 even moderately satisfactory, can the psycholo- 

 gist to-day base any definite conclusion as to 

 what goes on in the retina or in the brain dur- 

 ing the act of vision ? Can it be confidently 

 said that we are yet much wiser than our grand- 

 fathers were in relation to this elusive problem ? 

 These skeptical questions are not meant to im- 

 ply any lack of esteem for the valuable work 

 which has been done in psychology, or of ad- 

 miration for the great ability that is at present 

 directed toward the solution of the difficulties 

 which the psychologist boldly attacks. In ac- 

 cepting the hypothesis of Young that three 

 diiTerent sets of nerves respond to the three 

 fundamental color sensations Helmholtz fully 

 recognized its uncertainty. He considered it 

 equally probable that each fibril might serve 

 for three activities completely distinct and in- 

 dependent of each other. {Handbuch der physio- 

 logiachen Optik, p. 292.) This theory has been 



found so satisfactory from the physicist's stand- 

 point that it is hard to see what advantage 

 would be gained by rejecting it until something 

 else is presented that can be established on 

 better evidence. The case is quite analogous 

 to the physicist's acceptance of the all-pervad- 

 ing, elastic, incompressible ether as the me- 

 dium through which physical energy is propa- 

 gated. The existence of some sort of medium 

 in space has to be postulated as a necessity of 

 thought ; its properties we infer from the phe- 

 nomena which are explained on the given as- 

 sumption. The acceptance is provisional only ; 

 we are ready to abandon it as soon as better 

 evidence is presented in behalf of some other 

 theory. Thus far there has not been even a 

 suggestion of better evidence. 



If now the psychologists can all agree upon 

 some theory which is quite as consistent with 

 known facts, and which involves less violent 

 assumptions than does the theory of Young 

 and Helmholtz, the physicists will assuredly be 

 ready to welcome what seems to be new truth. 

 To criticise is much easier than to construct. 

 There is practical unanimity among the physi- 

 cists just at present, but for the psychologists 

 the same can by no means be said. For some 

 time the leading competitor of the Young and 

 Helmholtz theory was that of Hering — a theory 

 which is less simple, and based on assumptions 

 quite as difficult. But we are now informed 

 that "there is one important university in this 

 country in which the theories of Helmholtz 

 and Hering have both been definitely given up, 

 and particularly in the physical department." 

 Granting this, the physicists elsewhere are justi- 

 fied in asking what they should now accept, and 

 what are the positive grounds for acceptance. 

 Several new theories of vision have been pro- 

 pounded within the last few years. One is by 

 Ebbinghaus {Theorie des Farbenaehens, 1893); 

 another, which is very attractive, is due to 

 Mrs. Franklin ; and still another, by Nicati, 

 has been brought forward within the last few 

 months. This is somewhat bewildering for the 

 physicists, who must be modest enough to wait 

 until the psychologists come to an agreement 

 among themselves. It may be true that the 

 Helmholtz theory is preevolutionary and pre- 

 psychological ; but the physicists have their 



