THE ORIGIN OF RIGHT-HANDEDNESS. 607 



planned with very great care and with especial view to the test- 

 ing of several hypotheses which, although superficial to those 

 who have studied physiology, yet constantly recur in publications 

 on this subject.* Among these theories certain may be men- 

 tioned which my experimental arrangements were aimed to test. 

 It has frequently been held that a child's right-handedness arises 

 from the nurse's or mother's constant method of carrying it ; the 

 child's hand which is left free being more exercised, and so be- 

 coming stronger. This theory is ambiguous as regards both 

 mother and child. The mother, if right-handed, would carry the 

 child on the left arm, in order to work with the right arm. 

 This I find an invariable tendency with myself and with nurses 

 and mothers whom I have observed. But this would leave the 

 child's left arm free, and a right-handed mother would be found 

 with a left-handed child. Again, if the mother or nurse is left- 

 handed, the child would tend to be right-handed. Or if, as is the 

 case in civilized countries, nurses replace the mothers, it would 

 be necessary that most of the nurses be left-handed in order to 

 make most of the children right-handed. Neither of these posi- 

 tions is true. Further, the child, as a matter of fact, holds on 

 with both hands, however it is itself held. Another theory main- 

 tains that the development of right-handedness is due to differ- 

 ences in weight of the two lateral halves of the body ; this tends 

 to bring more strain on one side than the other, and so to give 

 more exercise to that side. This evidently assumes that children 

 are not right or left handed before they learn to stand. This my 

 results giveD below show to be false. Again, we are told that in- 

 fants get right-handed by being placed on one side too much for 

 sleep : this can be shown to have little force also, when the pre- 

 caution is taken to place the child alternately on its right and left 

 sides for its sleeping periods. 



In the case of the child H certain precautions were care- 

 fully enforced. She was never carried about in arms at all never 

 walked with when crying or sleepless (a ruinous and needless 

 habit to cultivate in an infant) ; she was frequently turned over 

 in her sleep ; she was not allowed to balance herself on her feet 

 until a later period than that covered by the experiments. Thus 

 the conditions of the rise of the new right-handed era were made 

 as simple and uniform as possible. 



The experiments included, besides reaching for colors, a great 

 many of reaching for other objects, at longer and shorter dis- 

 tances, and in unsymmetrical directions. The following table (I) 



* Cf. Vierordt's remarks, Physiologic des Kindesalters, pp. 428, 429. For a detailed 

 statement of theories on this topic, see chapter x of the very learned monograph on The 

 Right Hand : Left- ban dedness, by my late lamented colleague and friend Sir Daniel Wilson. 



