"Sometimes a fish is male on one side, female on the other, or male anteriorly and female posteriorly.... Among invertebrates the same has been occasionally observed, especially among butterflies, where striking differences in the colouring of the wings on the two sides have in some cases been found to correspond to an internal co-existence of ovary and testes.... The prettiest cases of superficial hermaphrodism occur among insects, especially among moths and butterflies, where it often happens that the wings on one side are those of the male, on the other, those of the female." II Despite the fact that Nature has evolved the complex human races from the single-celled microscopic _amoeba_ ("Protoplasmic father of Man," as science has styled this), there are those who regard it as another of numerous blunders on the part of the Great Mother that the left side of the body is a more or less passive and powerless member. Accordingly, the doctrine of Ambidextry has arisen. With the result that its wiser exponents have abandoned it. Because it has been found that children trained on Ambidextrous lines develop neurotic symptoms. This occurs even in cases in which children naturally left-handed are taught to use the right hand, as is normal. In a lecture given before The Child-Study Society in London, Mr. P. B. Ballard, London County-Council Inspector of Schools, stated that left-handed bowlers send down the ugliest balls, left-handed boxers deal the most unexpected blows--blows that hurt terribly. To be left-handed, it seemed, was to be not merely awkward, but to be wicked, moreover. Yet any attempt to interfere with a child's natural habit is liable to make him stammer. (The evil bent of left-handed persons has a special significance in view of my hypothesis of the dissimilar mental functions of the two brain-hemispheres. The term "sinister" expresses this bent. The inference is that in such transposition of the normal functions of the brain-halves, the tempering and humanising influence of the Woman-half is counteracted.) Of a group of 545 left-handed children, 1 per cent. of pure left-handers stammered, against 4·3 per cent, of 399, in course of being taught to use the right hand, Mr. Ballard further stated. In another group of 207, the figures were 4·2 per cent, and 21·8 per cent. respectively. Six out of ten left-handed children who had been taught to use the right hand were practically cured of stammering after having been allowed to use the left hand exclusively for eighteen months. There are twice as many left-handed boys as left-handed girls; and stammering is twice as prevalent among boys. All of which indicates normal differences in function of the two sides of the body--differences suggesting that, as I have surmised, each is the site and the agency of a principle totally unlike that of the other. III