Literaiy Notices. xlix 



New unsymmetrical functions give a differential or two-fold organic 

 development, the great instance of which is found in the cerebral 

 hemispheres. New symmetrical or unilateral functions find their 

 counterpart each in one of three kinds of nervous adaptation: (a) Co- 

 ordination of the hemispheres in a single function — i. e., functions 

 which are crippled if either hemisphere is damaged; (b) Co-ordina- 

 tion of particular functions in each hemisphere — i. e., functions which 

 are not crippled unless both hemispheres are damaged; and (c) Co-or- 

 dination of particular functions in one hemisphere only — i. e., func- 

 tions which are crippled if one selected hemisphere is damaged. Both 

 speech and the right-handed function come under the last head. 

 These functions have in common their expressive character. "Upon 

 this view it is easy to hold that right-handedness is a form of expres- 

 sive differentiation of movement, and that it preceded speech, which 

 is a further and more complex form of differentiation and adaptation." 

 In the instances reported the following facts support the theory : 

 i. Right-handedness arose before speech. 2. Imitation by the hand 

 of movements seen to arise before articulate imitations of sounds heard. 

 3. Characteristic differences in children in respect to their general 

 mobility of arm and hand, manual skill, etc., extend also to speech. 

 Musical ability is also associated with speech ability. As to the origin 

 of the asymmetry it is suggested that spontaneous variations giving ad- 

 vantageous dextrality would arise and persist as soon as these func- 

 tions were liberated from the influence of bilateral motions. It is 

 likely, therefore, that right-handedness in the child is due to differ- 

 ences in the two half-brains, reached at an early stage in life, that the 

 promise of it is inherited, and that the influences of infancy have little 

 effect upon it, the speech function being a further development of the 

 same unilateral potency for movement found first in right or left-hand- 

 edness. 



Muscular Sense of the Blind. 



Hocheisen in an article in the Zeitschrift f . Psych, u. Phys. d. 

 Sinnesorgane, V, p. 239, applies Goldschneider's methods of research 

 to the blind, making 9000 experiments to determine how great an 

 angular motion of a joint is required to be perceived as motion. He 

 found a small but demonstrable increase in the fineness of the dis- 

 crimination which is greater in the young. Localization is said to be 

 but little more acute in the blind and the increased muscular discrimi- 

 nation is referred to development of attention. It is, in other words, 

 due to purely psychical causes. Small motor acts play a large part in 

 the reading of the blind. 



