774 



SCIENCE. 



FN. S. Vol. VII. No. 179. 



irig's theory of Color Vision he has been content 

 for several years to know the subject only in 

 the compendiums of Helmholtz, Wundt and 

 Hermann, and in the original paper of Hering 

 of 1874, and yet he iinds himself able to lay 

 down the law in an ex-cathedra fashion that 

 one would usually not be willing to indulge in, 

 in regard to a confessedly undecided question, 

 after a long devotion to the subject. That his 

 reading has been cursory, aud has been ap- 

 parently to a certain extent forgotten, is 

 evident from his making in a few lines such 

 mistakes as to attribute the idea of the shift of 

 excitability in photo-chemical substances to 

 Konig, and to refer to the Helmholtz theory as 

 a three-fibre theory. Fick is usually and not 

 improperly credited with the idea of the ' shift 

 of excitability, ' as it is he who first made much 

 of it in the explanation of color-blindness, but 

 the idea is originally due to Helmholtz himself, 

 and occurs already in the first edition of his ' Op- 

 tics.' To say, therefore, of Helmholtz's theory 

 that ' its original and most attractive simplicity 

 has been given up in favor of Konig' s shift of 

 excitability ' is to show a rather unusual degree 

 of ignorance of the facts of the case. It is also 

 doing much injustice to the Helmholtz theory 

 to designate it as a three-fibre theory ; the as- 

 signment of the three chemical substances to 

 three separate fibres was, in the first edition of 

 the 'Optics, ' expressly stated to be merely a mode 

 of facilitating speaking about them, and since 

 the time of its experimental disproving in 

 Helmholtz' own laboratory it has naturally 

 been abandoned by him. 



The present discussion of color-vision in 

 Science has been occasioned by Professor Pat- 

 ten's having had the temerity to bring out an 

 entirely new theory, the main feature of which 

 is that it is an endeavor to take account of a 

 peculiarity of the structure of the retina which 

 is certainly there, and which as certainly does 

 not exist without having some function. Pro- 

 fessor Patten's full paper on the subject has not 

 yet appeared ; when it does it will no doubt re- 

 ceive a due measure of attention from the 

 physiologists aud the anatomists, to whom it 

 makes its chief appeal ; any great psycholog- 

 ical inadequateness is hardly to be looked for, 

 at the hands of its author, in view of the full dis- 



cussion which considerations of this sort have re- 

 ceived in recent years. But it seems hardly cour- 

 teous to condemn a theory before it has had a 

 chance to be heard; any new theory, from the na- 

 ture of the case, makes its appeal to those only 

 who have the leisure and the open-mindedness 

 (or the idle curiosity, as it may turn out to have 

 been) to give it a fair share of attention. 

 For a fresh theory to be set down as unneces- 

 sary and absurd is no new experience ; the 

 most recent (and classical) example of the sort 

 is the notice with which Kolbe greeted Van 't 

 Hoff 's conception of the different positions of 

 atoms in space, which has since assumed such 

 fundamental importance for chemistry. He 

 said: "If any one supposes that I exaggerate 

 this evil [of erratic speculation] I recommend 

 him to read, if he has the patience, the recent 

 fanciful publication of Van't Hoff and Her- 

 mann ' ' (Hermann being the German translator). 

 It cannot, therefore, be looked upon as alto- 

 gether a bad omen that the first feeling excited 

 by a new theory is one of irritation and im- 

 patience. 



My own theory met with the great good luck 

 that, at the end of a year after it was brought 

 out, the President of the British Association 

 happened to take, as the subject of his presiden- 

 tial address, a topic which included color-vision; 

 after full and careful discussion of the sub- 

 ject, he stated that the known facts in the case 

 (and especially those recently discovered) were 

 best explained by my theory. It is a piece of 

 good fortune, again, that the physiologists of this 

 country have happened just at this time to bring 

 out a large and important general work on 

 Physiology ; this has given Professor Bowditch 

 occasion to give my theory generous space and 

 a very fair showing. As a Vice-President of 

 the American Association, Professor Le Conte 

 Stevens has also happened to have color-vision 

 for the subject of his inaugural address ; and the 

 author of the best English compendium on sight. 

 Professor Joseph Le Conte, has happened to 

 bring out a new edition of his little book ; I 

 have to thank them both for the courteous 

 treatment which they have given my attempt 

 to account for the phenomena of the sensation 

 of light. All this I regard as a piece of good 

 fortune, such as does not always attend upon 



