14 WILLIAM JAMES ON 



worth while to observe, however, that the feeling of accommodation and the knowledge 

 of the true size of the object conspire with the feeling of convergence to give the 

 judgment of distance. And where the convergence is an altogether abnormal one, 

 as in the paretic squint, the feeling of the left eyeball being excessive, might well 

 simply overpower all other feelings and leave no clear impression whatever save a general 

 one of looking far towards the right. 



The only thoroughly crucial test of the explanation here proposed of the paretic 

 translocation, would be a case in which the left eye alone looked at the object whilst 

 the right, looking at nothing, strongly converged. Since, however, the only way 

 of making a normal eye converge, is to give it an object to look at, it would 

 seem at first sight as if such a case could never be obtained. It has occurred 

 to me, notwthstanding, that slight atropinization of one eye might cause such strong 

 accommodative innervation, that the convergent muscles might symj^athetically contract, 

 and a squint tend to occur. The squint would be steadfast, and situated in the 

 non-atropinized eye, if it were covered and the poisoned eye alone made to fixate 

 a near object. And if under these circumstances the object thus monocularly seen were 

 translocated outwardly, we should have a complete verification of the explanation 

 I present. The innervation is wholly different from that in paresis, and the only point the 

 two cases have in common is the covered eye rotated nasalwards. Probably it would 

 not be easy to find the patient, or the dose of atropia just fitted for producing the 

 squint. But one positive instance would outweigh a hundred negative ones. 1 have 

 had a chance to experiment on but one person. A large needle was stuck in a 

 horizontal board, whose edges touched the face, the needle being from eight to twelve 

 inches in front of the right atropinized eye. The subject was told to touch with her 

 fino-er the under surface of the lioard, just beneath the needle. The results were 

 negative, — no well-marked squint being perceptible, — but on the third day after 

 the atropinization, the patient regularly placed her finger from one-half to three-quarters 

 of an inch too far to the right. Other observations ought to be made. 



o 



There seems meanwhile to be a very good negative instance by which to corroborate our 

 arguments. If we whirl about on our heel to the right, objects will, as above-mentioned, 

 seem to whirl about us to the left as soon as we stand still. This is due to the 

 fact that our eyes are unwittingly making slow movements to the right, corrected 

 at intervals by quick voluntary ones to the left. There is then in the eyes a permanent 

 excess of rightward innervation, the reflex resultant of our giddiness. The intermittent 

 movements to the left by which we correct this, simply confirm and intensify the impres- 

 sion it gives us of a leftward whirling in the field of view : we seem to ourselves to be 



one of the double images of a more distant object whose other The only experiment capable of proving the theory advanced 



double image is cut off by a screen from the left retina. in the text would be one in which no shifting of the image 



Under these circumstances we get translocations which may on the right retina accompanied the turning inwards of the 



be similar to those in paresis but they prove nothing to our left eye. Tlie experiment without prisms mentioned by 



purpose, for the moment the prism is introduced before the Herlng, (Lehre vom binocularen Sehen, pp. 12-14), seems 



left eye, altering its convergence, the right eye moves the nearest approach which we can make to this, but there 



sympathetically, giving rise to a translation of its retinal both eyes fixate the same objects, and there is some trans, 



image, which of course suggests translocation of the object. lation of the image. 



