It seems that sufficient care has not yet been taken to determine what constitutes left-handedness. The relative strength of the two hands is not enough to decide this, for mancinism, or left-sidedness, is a matter of relative skill as well as of relative strength. It is quite possible for a person to be left-handed in some respects, right-handed in others; thus (as happens to be the case with the present writer) he may be right-handed in regard to all those actions which are exercised habitually and socially, or which are the result of training, and left-handed in all other respects. In such a case there appears to be a natural tendency to left-sidedness, which is controlled and concealed by training, but which takes every opportunity to assert itself in more unguarded directions. It appears to me that the act of throwing a stone, an act requiring delicate nervous adjustment as well as muscular force, and which is not subjected to the influence of artificial training, is for practical purposes the most convenient and accurate test for determining left-handedness. This was the test adopted by Clapham and Clarke; they found that 6 per cent. of the 500 criminals examined were left-handed.[39] Ottolenghi has recently investigated the anatomical mancinism of criminals. At the suggestion of Lombroso, he has measured with Bertillon’s instruments, which give the maximum of precision, the length of the hands, the middle fingers, and the feet in 100 criminals and 50 normal persons. Differences of less than a millimetre he disregarded. He found that while the right hand was longer in 14 per cent. of the normal persons, it was so in only 5 per cent. of the criminals generally, and in none of the thieves and pickpockets. In 35 per cent. of the pickpockets the left hand was longer as against 11 per cent. in the normal persons. Very similar results came out in regard to the fingers. In 38 per cent. of the normal persons the right foot was longer, in only 27 per cent. of the criminals; in this respect, however, the pickpockets (35 per cent.) most nearly approach the normal, while those convicted of wounding, who in regard to the hand are nearest to the normal, are in this respect farthest from the normal. In 15 per cent. of the normal persons the left foot was longer, in 35 per cent. of the criminals, including 55 per cent. of the cases for wounding, and in 56 per cent. of the sexual offenders. It should be added that this anatomical mancinism is not necessarily related with motor mancinism.[40]