PHYSICAL CHARACTERS IX MAN 73 



basis for these conclusions. Jordan, from an 

 examination of 700 university students, 1,394 

 coloured school children, and 668 others, concludes 

 that the condition is inherited, but is not very clear 

 that it follows Mendelian principles. Baldwin f(jund 

 that the tendency to use one hand more than the 

 other developed about the seventh month after birth, 

 when all influences to the greater use of one hand 

 were ehminated. The old idea that right-handedness 

 was developed because warriors held the shield with 

 their left hand to protect their heart and wielded the 

 spear with their right will not bear analysis with 

 modern conceptions. That right- or left-handedness 

 does not depend on a difference in the eyes is also 

 shown by the fact that there is the same proportion 

 of left-handed among the congenitally blind as among 

 those who use their eyes. 



Beeley considers the results from 106,356 children 

 examined, and concludes that all degrees exist from 

 extreme left-handedness to extreme right-handedness. 

 Among this number of children were found fort}'- 

 two " mirror- writers." The results showed that 

 mirror- writing is not necessarily correlated with 

 mental deficiency, but rather it is characteristic of 

 extreme left-handedness. A method was devised 

 for measuring the degree of left-handedness by means 

 of a brass plate divided into squares, on which two 

 straight lines at right angles to each other were to be 

 traced. The squares were alternately insulated in 

 such a way that ever}^ error produced an electric 

 current which was recorded in a counter. The number 

 of errors in tracing the two lines, multiplied by the 

 time taken, was used as a measure of the degree of 

 left-handedness. Obviously general dexterity would 

 play an important part in a result of this kind, and 

 the age of the child would be an important element in 

 such a result. It is not, therefore, clear that the degree 



