Apbil 8, 1904.] 



SCIENCE. 



593 



that does not give evidences of the influence 

 of right-eyedness. 



One wonders if a new clearness will not be 

 brought into neurology and psychology by a 

 careful correlation of the suggestions which 

 the theory offers. The unification and per- 

 fection of innervation and cerebration must 

 be better if initiated and executed with the 

 cerebral centers mainly upon one side of the 

 brain, than if the unity is gained by means of 

 the longer and more distant commissural 

 fibers extending between the two sides of the 

 brain. In the right-handed the speech center 

 is in the left side of the brain, as is also the 

 innervational motor center for the right hand, 

 and the optical center of the right eye. The 

 • dependence of all motion upon a perfect corre- 

 lation of vision and judgment needs only to 

 be mentioned. That all intellect is psycho- 

 logically the product of vision is less recog- 

 nized, but is not less absolute truth. The 

 right hand writes, possibly because the right 

 eye looks down upon the writing more ac- 

 curately than would the left; both depend 

 upon the synchronous and closely interrelated 

 guidance of the speech-making function. All 

 three are in closer unity and contiguity than 

 if either were in the opposite side of the skull. 

 A gentleman acquaintance who is left-handed 

 for most things has by training during youth 

 developed the habitual use of the right hand 

 for writing. When he plays billiards he takes 

 aim two or three times as long as others, and 

 makes from six to ten motions with the cue 

 before giving the stroke. One feels that his 

 correlation of vision, judgTnent and motion is 

 much more difficult than with other players. 



In the left-handed, as is well known, the 

 speech center is in the right brain. Hence 

 the left-handed are also left-eyed. 



The pathologic presents itself when in the 

 right-handed by heredity or habit, right-eyed- 

 ness is prevented by a greater ametropia in 

 the right, by accident, injury, cataract, 

 leucoma or other disease which markedly 

 lessens its visual acuity below that of the 

 left. Eight-eyedness, however, will persist 

 with considerably greater acuity of the left 

 eye. To be right-handed by heredity and 

 habit, and at the same time left-eyed by dis- 



ease, etc., brings a doubt and an awkwardness 

 into every act. After a half-life of right- 

 eyed correlations and habits to be suddenly 

 made left-eyed, etc., by disease, accident, or 

 by glasses produces something like tragedy 

 in a patient. Many problems and ill-suc- 

 cesses in the practising ophthalmologists' 

 office receive an illuminating explanation by 

 keeping in mind the physiologic fact of right- 

 eyedness and the pathologic consequences of 

 disease, or the result of interfering with it, 

 by spectacle lenses. It may be better for the 

 oculist to leave a person right-eyed rather than 

 to give such lenses as suddenly compel left- 

 eyedness. 



For the present I will cite only three illus- 

 trative cases : 



The first is that of a man who is left-handed 

 in billiard playing and in most occupations. 

 Asked to see if his cue was straight, he brought 

 it before the nose with both eyes open, and 

 thus ' sighted ' along it. Asked to sight more 

 accurately, he finally brought it opposite the 

 right eye and closed his left. Asked to ob- 

 serve if two tables were exactly of the same 

 height, he again sighted with the right eye, 

 shutting the left. And he wrote vsdth his 

 right hand. These acts at first seemed to be 

 incongruous, but they were all explained by 

 the fact that his right arm had been broken 

 when he was twelve years of age, and the 

 right-handed acts since then performed with 

 the left have been compelled because of per- 

 manent injury of the right arm. Writing 

 being largely a finger-movement, and espe- 

 cially an intellectual act, was continued with 

 the right hand. It has been demonstrated by 

 pathology that the intellectual act of writing 

 proves the location of the speech-center to be 

 in the side of the brain opposite the hand 

 used, although for all other usually right- 

 handed acts the left may be preferred. 



The second case is that of a c'mrpenter who 

 is left-handed, and has been so from infancy. 

 He is also left-eyed. During his youth 

 parents and teachers tried to make him right- 

 handed by tying his left hand behind him, 

 etc. As a carpenter he has to use tools, the 

 plane, a vise, etc., made for the right-handed, 

 but he is always awkward when thus com- 



