BILATERAL ASYMMETRY OF FUNCTION. 97 wider and shorter ; and Petit asserted that new-born children breathe first with the upper lobe of the right lung. It has been said that of organs in pairs, those on the right side are apt to be slightly farther to the front. On the relative size of the kidneys, observations differ ; but the gravid uterus more often inclines to the right, and the umbilicus is turned to the left. The average predominance in weight of the viscera of the right side is, according to Buchanan, about 15 oz., and in deep inspiration the centre of gravity is shifted slightly backward and to the right, and makes that side freer and readier for action. Pathological, which is so closely connected with vaso-motor, asymmetry is very common, and many morbid processes are arrested at the median line. Semeiology infers, from the widening of one pupil, which of internal double organs is most diseased. Fevers and the resulting weakness are greatest on the right, which is also affected most and soonest by organic and mineral poisons, blisters, and intoxicants, so that convulsions which begin on the left side are rarely of toxic origin. In opis- thotonus, the body curves to the right. Of seventy cases of pneumonia observed by one writer, sixty were on the right side ; the complications due to stenosis are often unilateral. Sick head- ache, or hemicrania, which alternately attacks the right and left side, is severer on the latter. If there is congenital or degene- rative left-sidedness, or if an ear, lung, kidney or other organ or member is defective or wanting, it is likely to be on the left side, which is also more likely to be the seat of anaemia, atrophy, can- cer, and, according to one opinion, epilepsy. These may be called diseases of arrest or defect, which one writer thinks favoured by summer, while all that augments nutrition, as, for example, cold weather, favours those diseases which affect the right side most strongly, and at the same time resists sinistral maladies. On this side also extra thumbs, toes, and other organs and hyper- trophies are most common. From this general asymmetry animals are not exempt, though most observations are far less reliable. It has been stated by scientific men that double organs in the horse, dog, or other ani- mals, are larger on the right side ; that worms, in starting, writhe to the right first. Flierdl states that mollusca roll to the right by preference. It has been said that parrots prefer to stand on, and dogs to lift, the right leg. Huber observed an ant to run around about one thousand times an hour for seven days in a circle of an inch in diameter, indicating thereby incoordination of the two halves of the nerve centre. It is probable that the alleged ambi- dexterity of monkeys and infants is only relative. One of us observed an infant of nine months, whose hands were held symmetrically to its sides and freed at the same instant, grasp a desired object placed directly in front of it on the table fifteen times out of twenty with the right hand, often even when the object was placed somewhat to the left. Professor Brewer, who
