THE ORIGIN OF RIGHT-HANDEDNESS. 613 



par excellence the function of expression. It is further only a 

 part of the position upon which the psychological theory of ex- 

 pression is based, that all movements are in so far expressive, and 

 that details of expression and its relative fullness are matters of 

 co-ordination. Now, this co-ordination has attained its ripest and 

 most complex form, apart from speech, in movements of the hand. 

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

 of expressive differentiation of movement, and that it preceded 

 speech, which is a further and more complex form of differentia- 

 tion and adaptation. 



The neurological basis upon which this hypothesis rests is 

 adequate, and affords a presumption as to the psychological devel- 

 opment as well. The facts I have now given, for the first time, 

 go some way to support the view : 1. Right-handedness arose be- 

 fore speech in the child H . 2. Imitation by the hand of move- 

 ments seen arise before articulate imitations of sounds heard ; * 

 this in spite of the fact that hearing, in its development in the 

 child, becomes perfect before sight. 3. Characteristic differences 

 in children in respect to their general mobility of arm and hand, 

 manual skill, and quickness of manipulation, extend also to sj)eech. 

 As compared with my other child, E , the first-born, H , is re- 

 markably agile and motile generally in her temperament ; and her 

 speech development was relatively much earlier and more rapid. 



It is further interesting to note that musical ability is asso- 

 ciated with speech ability a connection which would be expected 

 when one takes due account of the expressive character and func- 

 tion of music. As far as theories of the rise of musical expression 

 have gone, they unite in finding its beginnings in the rudiment- 

 ary emotional expressions of the animals. The singing of birds is 

 undoubtedly connected with their mating instincts. Pathologi- 

 cal cases also show a marked connection between musical execu- 

 tion and speech, to the extent that, while musical defect almost 

 invariably involves speech defects, the reverse is much less gen- 

 erally true a fact which confirms the view that music is an ear- 

 lier form, but still a form, of expressive reaction. 



Late observations also show, as far as they are sufficient, that 

 the center for music expression is also located normally in the 

 left hemisphere for right-handed persons. Oppenheim reports a 

 case t of total aphasia with total amusia (lack of musical ability 

 from disease) in which the recovery of speech brought with it 

 musical recovery also. Furthermore, another case of Oppen- 

 heim's shows motor aphasia with motor amusia only i. e., the 



* It is interesting that of both hand and speech movements the latest to be lost in dis- 

 ease are those involved in the so-called " mimicry " of movement and in imitative speech, 

 f Charite Annalen, xiii, 1888, p. 286. 



