HAND AND LEFT-HANDEDNESS. 241 
efficiency without any counteracting awkwardness or defect. In certain arts and pro- 
fessions, both hands are necessarily called into play. The skilful surgeon finds an 
enormous advantage in being able to transfer his instrument from one hand to the other. 
The dentist has to multiply instruments to make up for the lack of such acquired power. 
The fencer who can transfer his weapon to the left hand, places his adversary at a 
disadvantage. The lumberer finds it indispensable in the operations of his woodcraft 
to learn to chop timber right and left-handed; and the carpenter may be frequently seen 
using the saw and hammer in either hand, and thereby not only resting his arm, but 
greatly facilitating his work. In all the fine arts the mastery of both hands is advan- 
tageous. The sculptor, the carver, the draftsman, the engraver, and cameo-cutter, each 
has recourse at times to the left hand for special manipulative dexterity; the pianist 
depends little less on the left hand than the right; and as for the organist, with the 
numerous pedals and stops of the modern grand organ, a quadrumanous musician would 
still find reason to envy the ampler scope which a Briareus could command. On the other 
hand, it is no less true that, while the experience of every thoroughly left-handed person 
shows the possibility of training both hands to a capacity for responding to the mind 
with promptness and skill, at the same time it is none the less apparent that in cases of 
true left-handedness there is an organic specialization which no enforced habit can wholly 
supersede. 
The conclusion at which I finally arrive is that left-handedness is due to an excep- 
tional development of the right hemisphere of the brain. I have long delayed the printing 
of this monograph on the subject, in expectation of some response to appeals I have 
repeatedly made to medical friends, in the hope that the occurrence of some strongly 
marked case of left-handedness among hospital or other patients might afford an oppor- 
tunity of bringing it to the test. But in the passive condition of mortal disease there is 
little occasion to draw attention to the left-handed action of a patient; and I must leave 
the point to be determined hereafter under some favouring opportunity. My own brain 
has now been in use for more than the full allotted term of three score years and ten, and 
the time cannot be far distant when I shall be done with it. When that time comes, I 
should be glad if it were turned to account for the little further service of settling this 
physiological puzzle. If my ideas are correct, I anticipate as the result of its exam- 
ination, that the right hemisphere will not only be found to be heavier than the left, 
but that it will probably be marked by a noticable difference in the number and arrange- 
ments of the convolutions. 
Nore.—The subject which is fully dealt with in the above paper has been previously considered by the writer 
in some of the aspects here reviewed. He has now embodied these, along with the results of more recent investi- 
gations. See “ Right-handedness,” Canadian Journal, N.S., 1871, Vol. xiii. p. 193 ; “ Left-handedness,” Zbid., 1872, 
Vol. xiv. p. 465 ; “ Primeval Dexterity,” Proceedings of the Canadian Institute, 1885, Vol. iii. p. 125 ; “ Palzeolithic 
Dexterity,” Transactions of the Royal Society of Canada, 1886, Vol. iii. See. ii. p. 119. 
Sec. II. 1886. 6. 
