June, 1913. 



KNOWLEDGE. 



207 



According to Bolk, right-handedness is connected 

 with " the better nourishment of the left cerebral 

 hemisphere which is the nerve centre for the right 

 half of the body." According to Biervliet, " the 

 nervous system also participates in asymmetry." 

 Professor Buschan wrote in 1902 : — " In a large 

 majority of cases the right side of adult bodies is 

 the more fully developed, with the exception of the 

 left leg. . . . The activity of the nervous system is 

 always greater on the more fully developed side. If 

 the right ear is the stronger it never happens that 

 the left eye sees best. One is born either right- 

 handed or left-handed, and it is impossible to train 

 a left-handed person to be right-handed, or the other 

 way about." 



Other investigators deny that it is " inborn " and 

 it is also frequently asserted that left-handedness can 

 be overcome. Among the numerous right- and left- 

 handed persons examined by two German doctors, 

 Langstein and Hecht, there was a young soldier who 

 was originally left-handed, and had overcome the 

 habit of chiefly using his left hand, although wjth 

 difficulty, when learning his trade, and afterwards 

 during his military service, and for years he had 

 worked easily with his right. Yet, whenever he was 

 in need of special dexterity he made use of the left. 

 It seems possible to get rid of left-handedness, not 

 alone by habit, but also by hypnotic suggestion. 

 Such an experiment was made by a doctor on a left- 

 handed child of four. The child's right hand was 

 held when she was in a hypnotic state, and she was 

 told to make more use of it in the future. The 

 effect of the suggestion was surprising, for the gjrl 

 began to use her right hand more from that time, 

 and after the third treatment given in the course of 

 a few days, she became right-handed, and has 

 remained so. The report in the Wiener Klinische 

 Wochenschrift reads : — " Quite apart from its 

 therapeutic success this case is of peculiar 

 interest because the effect of suggestion upon left- 

 handedness seems to establish that even when 

 left-handedness is developed in childhood, already 

 the two cerebral hemispheres may have originally 

 had equal capacities. The case not only argues 

 against the theory that the superiority of the right 

 half of the brain is the cause of left-handedness, but 

 maintains that it must certainly be possible to 

 prevent left-handedness through early training." 



The following extracts, published anonymously in 

 the Frankfurter Zeitung, are worth noticing. They 

 recall the conjectures of Carlyle and Weber 

 mentioned above. " The preponderance of the 

 right hand is not a primeval gift, but an achieve- 

 ment of civilisation, an outcome of the progressive 

 corporeal and mental differentiation and division of 

 work. When man became man, when the build of 

 his body enabled and compelled him to walk 

 upright, the right and left hands must have been of 

 equal importance to him. While the legs and feet, 

 as organs of locomotion, still preserve equal rights 



and duties, the activity of the arms and hands, 

 which was destined to a fuller development, was 

 distributed in such a way that the left hand plays a 

 passive, holding and shielding part, and the right 

 hand an active, seizing and attacking one. The 

 preponderance of the right hand must have been a 

 secondary phenomenon in the first instance. Combat 

 was at that time the principal thing — primeval 

 instinct was a surer guide in orientation than the 

 observation of the stars — and the need in combat 

 with man and beast to shield the most vital part of 

 the body, the heart, with the armed or unarmed left 

 necessitated that the club, axe, knife or spear should 

 be held in the right. This habit was carried into 

 peaceful pursuits. Since the day of primeval man- 

 hood, even after the original cause had ceased to 

 exist, the preponderance of the right hand was 

 developed and established more and more in 

 civilised nations through heredity and education. 

 This differentiation is even to-day less marked in 

 some primitive races, and there is also to some 

 extent less distinction made between the upper 

 and lower limbs (prehensile foot). Our children 

 are in a similar position, and must, in fact, be 

 educated to the use and conventional higher appre- 

 ciation of the right hand. Thus the greater skill of 

 the right hand is occasioned by the structure of the 

 human body, the position of the heart, and perhaps 

 the nature of the aorta, together with man's relation 

 to the outer world and the primitive cause for a 

 stronger development of the right arm, to which 

 factors of civilisation have been added." 



Dr. Andrew Wilson has set forth an entirely new 

 theory.* With reference to the fact that the centre 

 controlling the movements of the right arm is 

 situated near the centre of speech in the left hemi- 

 sphere of the brain, he asks : " Is it not probable 

 that the superiority of the right side of our bodies 

 has kept step in growth with the development of 

 language ? " He denies right-handedness to be the 

 outcome of continued practice from childhood in the 

 use of the right hand, and considers it the result of 

 evolution from ambidexterity. Dr. Wilson gives no 

 explanation of left-handedness, to which Sir Daniel 

 Wilson has dedicated a whole book. 



The explanations given by the late Dr. Fritz 

 Lueddeckensf for left-handedness as well as right- 

 handedness are very detailed. This German doctor's 

 treatment of the subject is anatomical throughout, 

 and is based upon thorough investigation. The 

 keynote to his exposition is his unqualified rejection 

 of the theory that right- or left-handedness can rest 

 upon habit. Among other things, he says that the 

 hypothesis " is absolutely untenable that man should 

 more and more restrict the collaboration of one half 

 of the brain and become accustomed to the conse- 

 quent use of one hand if it were true that both 

 cerebral hemispheres had originally equal functions." 

 The mere anatomical fact that the centre controlling 

 the muscles for speech is fully developed on one 



* " The Light Side of Science." (Chapter on "Right-handedness.") 

 I "Die Ursachen der Rechts- mid Linkshiiendigkeit." Leipzig, HJ00. 



