238 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



ture researches concerning the physiology of the muscular 

 and nervous systems. 20^1,1871,355. 



DEXTRAL PRE-EMINENCE. 



Dr. William Ogle has recently made a communication to 

 the Royal Medical and Chirurgical Society of London upon 

 what he calls " dextral pre-eminence," in which he takes 

 ground against the most generally accepted doctrine that 

 the use of the right hand is based on conventional agreement, 

 enforced by educational influence, without the existence of 

 any natural tendency in physical formation. In support of 

 his views he remarks that the preferential use of one side is 

 not limited to the arm, but extends to the leg, which is not 

 subjected to education like the arms. The tendency to use 

 one side preferentially manifests itself before education be- 

 gins, and often persists in spite of efforts made to overcome 

 it. Left-handedness resembles many physical malformations 

 in being hereditary, in running in families, and in attaching 

 itself rather to the male sex than to the female. Statistics 

 are given of its relatively frequent tendency in the two sex- 

 es. The author also gave an account of his observations in 

 this matter upon other animals than man ; monkeys and par- 

 rots especially showing that they also have a tendency to use 

 one side preferentially. 



Having shown that there must be some one or other struc- 

 tural foundation for right-handedness, he next considers what 

 this may be, and states as the result of his inquiries that an 

 actual structural difference has been detected in many cases 

 between the two hemispheres of the brain, and that while the 

 left is the more complex in right-handed individuals, the con- 

 trary is the case with those who are left-handed. 



He also remarks that in most cases of the normal condi- 

 tion, namely, when the right-hand is used habitually, the left 

 hemisphere of the brain is larger, in consequence of receiving 

 a freer supply of blood than the right, the left arteries being, 

 as a rule, slightly larger than the right ones ; and independ- 

 ently of the size of the vessels, the stream of blood is less 

 on the left side than the right. This explanation is corrobo- 

 rated, according to the author, by the peculiarities of the cer- 

 ebral blood supply in those animals which manifest a tenden- 

 cy to use one side rather than the other, as in the case of 



