ACQUIRED DIFFERENCES. 9 



in many languages, while* the left has opposite associa- 

 tions. The Latin word sinister has a very definite conno- 

 tation both in Latin and English. The words sccevus and 

 Iceve meant left, incorrect, wrong. Among the Greeks 

 Se£i6$ meant right, that which is good, clever, skilful, 

 while <TKaio$ and apio-repos meant left, auguring evil, that 

 which is rude, foolish, awkward, even wicked. Right- 

 handedness is mentioned by Aristotle and Hippocrates ; 

 but we can trace it much further back. In ancient 

 Egyptian, Assyrian, and Babylonian Art the pen, the 

 brush, the tool and the weapon are almost always depicted 

 as being carried in the right hand. We may conclude 

 that civilised man has been right-handed for at least 

 6,000 years. 



The question of cause is also interesting. Among the 

 molluscs and crustaceans and probably in the pleuronec- 

 tidse, asymmetry has probably followed from an accidental 

 variation, which benefitted the animal by protecting it 

 or rendering the acquisition of food more easy. Being 

 the fittest in its competition with others, it has survived. 

 But how about the asymmetry in parrots, monkeys, apes 

 and man? Dr. Ogle believes the parrot tribe owe their 

 one-sidedness to extra blood supplied to the left brain. 

 He tells us that usually the brain is supplied by only one 

 vessel and that generally goes to the left side. He (as 

 also Dr. Wyeth, of New York*) applies this blood supply 

 theory also to the case of the Quadrumana and Man, he 

 believes that the left carotid artery is usually larger than 

 the right, and also that the blood stream entering the 

 left carotid meets with fewer angles in its course than 

 that of the right. Against this view it may be objected 

 that it is not proven that the left is any larger, and the 

 difference in angle is trivial, nor do the carotids 



* Annals of Anat. and Surg. Socy. of Brooklyn, 1880. 



