202 



SCIENCE. 



[N. S. Vol. III. No. 58. 



there is an image or a retina, however much 

 we may have formed the one and dissected the 

 other, it makes no difference whether the 

 image is inverted or not. With a proper dis- 

 tribution of nerve ends we could get on per- 

 fectly well with a three-dimensional image 

 formed in the vitreous humor in the interior of 

 the globe of the eye — ^what was once supposed 

 to be the scheme of vision, a scheme which 

 would have had the immense advantage of 

 saving us a lot of thinking in the effort to 

 understand how we see out- and in-ness. We 

 could also get on perfectly well if the flat image 

 which is actually produced were broken up into 

 a thousand parts, and the parts distributed upon 

 the retina in any confused order whatever, 

 provided the order were a perfectly fixed one, 

 and provided also (possibly) that the eyes were 

 immovable in the socket. 



While we are not conscious of the image nor 

 the retina, we are conscious of the movement 

 of the eye in the Socket. With the present 

 arrangement, when we reach the hand upward 

 to touch an object, we also move the eye up- 

 ward to fixate it, that is, the front half of the 

 ball of the eye, which is the part we are familiar 

 with on account of seeing its motion in other 

 individuals and in our own mirror. If the im- 

 age were not inverted and we had to move the 

 eye to the left at the same moment that we 

 move the hand to the right, there would then 

 be something to be explained, though this in- 

 congruity would doubtless be perfectly over- 

 come by experience.* 



I touched my little girl of eleven with a pen- 

 cil point on one corner of her eye and asked her 

 what she saw. "I see a i-ound whitish spot 

 over there," she said. "Is it not strange," 

 said I, "that when I touch you on the right, 

 you see something on the left?" "No," she 

 said, " I do not think it is strange at all." 

 What, said I to myself. Prof Le Conte is then 

 right, and all the psychologists are wrong — 



*If the eyeball be moved up and down by the 

 finger, objects looked at seem to move also. Prof. 

 James has suggested that some one try the experiment 

 of moving the eye in th'is way for many hours at a 

 time, and he predicts that here also experience would 

 have her perfect work, and that in time this apparent 

 motion of objects would no longer take place. 



this child is aware that rays of light cross 

 within her crystalline lens, and that when she 

 sees an object on the left it is because her re- 

 tina has suffered an affection on the right, in 

 spite of the fact that she has never heard of 

 retina or of crystalline lens ? But on question- 

 ing her farther I found that this was not the 

 case. She had formed a rapid hypothesis to 

 account for the otherwise unintelligible fact, 

 namely, that the pressure of the pencil was 

 communicated straight across the eyeball and 

 affected it on the opposite side. It had not 

 entered into her mind to conceive that a sen- 

 sation on the right was not due to something 

 going on in the right hand half of her eye, and 

 she had no intuitive idea of projection through 

 a point. 



The psychologist's view is thus summed up 

 by Professor James {Principles of Psychology, 

 II. , 42) : "I conclude then that there is n& 

 truth in the ' eccentric projection ' theory. It 

 is due to the confused assumption that the 

 bodily processes which cause a sensation must 

 also be its seat. It is from this confused as- 

 sumption that the time-honored riddle comes of 

 how, with an upside-down picture on the re- 

 tina, we can see things right side up. Our con- 

 sciousness is naively supposed to inhabit the 

 picture and to feel the picture's position as re- 

 lated to other objects of space. But the truth 

 is that the picture is non-existent, either as a 

 habitat or as anything else, for immediate con- 

 sciousness. Our notion of it is an enormously 

 late conception. * * * Berkeley long ago 

 made this matter perfectly clear (see his Essay 

 towards a New Theory of Vision, gg 93-98, 

 113-118)." 



Kiilpe, in his Outlines of Psychology, has at- 

 tached himself to the position of James and 

 Stumpf (and James mentions Professor Le Conte 

 as one of the two or three writers who have 

 given him most aid and comfort in supporting 

 his position) to the effect that retinal impres- 

 sions are from the first endowed with a spatial 

 quality, in opposition to Helmholtz and others,, 

 who regard visual space sensation as purely a 

 system of signs for effecting a one-to-one cor- 

 respondence with tactual space sensation. To 

 Professor James' argument, which is already 

 inexpugnable, Kiilpe adds the testimony of a 



