206 



KNOWLEDGE. 



June, 1913. 



the possible left-handedness of the sculptors in 

 question, but in deference to architectonic effect. 

 Even when a figure is represented holding a pen or 

 a sword with the left hand, it is only as an exception 

 which is to be traced back to considerations of 

 symmetry and perspective. Where such considera- 

 tions are not necessary, preference is always given 

 to the right hand. With regard to the monuments 

 of Central America testifying to a long vanished 

 civilisation, it is to be noted that the stone, figures 

 mostly face towards the left and will have been 

 chiselled, therefore, by right-handed artists. 



Separate designations, in different languages, of 

 the quarters of the heavens also speak for the age 

 and generality of right-handedness. Thus, for 

 instance, the Hebrew word "jamin" signifies both 

 " south " and " right hand." The same is the case 

 with the Sanscrit " dakschina," derivations of which 

 are to be found in most Indo-European languages, 

 and the like is to be met with elsewhere as well. 

 These double meanings originate in the fact that the 

 peoples in question took their bearings from the 

 position of the rising sun, and the south was, of 

 course, on their right. Sir Daniel infers from all 

 this that right-handedness is no chance or mere 

 habit, but is based on our physical and mental con- 

 stitution. The fact, therefore, that door-hinges and 

 handles, the spirals of a corkscrew, the adjustment 

 of scissors, and hundreds of other objects are all 

 calculated upon right-handedness rests upon valid 

 reasons. This deduction that there must be some 

 physical reason caused Sir D. Wilson to endeavour 

 to discover its nature. There is a great variety of 

 opinion on this point. The celebrated anatomist, 

 Barclay, for instance, a few decades ago, expressed it 

 as his opinion that the flow of blood was less as to 

 quantity and less regular on the left side than on 

 the right ; but Professor Buchanan, of Glasgow 

 University, maintained the theory that right- 

 handedness depends upon mechanical laws in 

 connection with the build and position of the 

 intestines ; thus the right lung has three lobes and 

 the left only two, and the liver, the heaviest organ 

 of the body, also lies on the right. Dr. Struthers 

 endeavours to strengthen Prof. Buchanan's theory 

 by asserting that the intestines to the right of the 

 median vein weigh twenty-two and three-quarter 

 ounces mere than those on the left. But the above- 

 mentioned scholars acknowledge, and acknowledge 

 respectively, that their theory is not able to account 

 for all the phenomena connected therewith. Sir D. 

 Wilson admits that the arrangement of the intestines 

 exercises some influence, but he seeks the chief 

 reason elsewhere — in the relationship between the 

 hands and the brain. As is well known, the two 

 cerebral hemispheres are the centres of the nervous 

 and muscular force in a contrary sense, the left 

 hemisphere governing the right side of the body and 

 the right hemisphere the left side. " Now the 

 left part of the brain is larger and has more convolu- 

 tions than the right, and it also receives a more 



direct flow of blood." * In forty brains Broca found 

 the left frontal lobe to be heavier than the right ; 

 and Boyd met with the same result in the examina- 

 tion of five hundred brains. It would thus follow 

 that in cases of left-handedness the right side of the 

 brain would, by way of exception, be heavier than 

 the left. Wilson naturally sought an opportunity 

 for a practical test of this conclusion. After several 

 years of expectation, the opportunity was offered by 

 the death of an incorrigibly left-handed soldier in 

 Toronto. In weighing the brain it was then found 

 that the right hemisphere really was heavier than 

 the left. 



A rather queer theory has been advanced by Dr. 

 F. Rosenberger. He connects the predominance of 

 the right hand with the apparent movements of the 

 stars, the need of taking orientation bearings in 

 space, and the consequent necessity for an artificial 

 division of the body into two asymmetrical halves, 

 the left one negative and the right positive, as well 

 as with the fact that an inhabitant of the higher 

 latitudes of the Northern Hemisphere, standing with 

 his face to the sun to take his bearings, can follow 

 the sun's course across the sky better with the out- 

 stretched right arm than with the left. Leaving 

 other improbabilities out of the question, Dr. 

 Rosenberger's hypothesis must be wrong from the 

 mere fact that the right-handedness of the inhabit- 

 ants of the Northern Hemisphere would then 

 necessitate the prevalence of left-handedness among 

 the dwellers in the Southern, which, however, is not 

 in the least the case. 



An attempt at an explanation made anonymously 

 in the Paris Nature is no happier. It maintains 

 that mothers more often present the better-developed 

 right breast to their infants, whose right arm is thus 

 less cramped and more able to make frequent 

 spontaneous movements, so that it strengthens 

 sooner than the left. Text-books on anatomy make 

 no mention of it, and personal information gathered 

 from experts partly denied it and partly maintained 

 the reverse. Nor can the hypothesis be proved that 

 children are more often carried on the right arm 

 than on the left. 



Other investigators assign the reason for right- 

 handedness to the asymmetrical position of the 

 heart and point out that owing to the construction 

 of the aorta the right side of the body has a stronger 

 supply of blood than the left, and that the right 

 arm thus has a distinct advantage through the 

 better nourishment of the muscles. The very 

 structure of the heart would, therefore, enforce 

 right-handedness. This, however, is not valid. 

 Apart from the fact that it has been proved 

 practically that it is not difficult fully to develop the 

 left hand, there exist animals, such as the gorilla, 

 chimpanzee, and seal, with a like anatomical structure 

 revealing no trace of a preference for one side or the 

 other. " In fact, it would be absolutely impossible 

 for birds to fly," remarks Dr. Stekel, rightly, "if they 

 were constructed so as to be right-winged." 



:: This is contradicted by many anatomists of our own day. 



