Page:Mind (Old Series) Volume 9.djvu/110

 !>"> G. STANLEY HALL AND E. M. HARTWELL. has not yet published his figures, found, of several thousand foot- marked horses, more white feet on the left than on the right side, the left hind-foot being most often marked, and the right fore- foot least often. Common spotted, as well as calico or " pinto," horses, have most white on the left side. The same rule, we are told, seems to hold with horned cattle, dogs, hogs, and perhaps wild animals where there is no possibility of fancy-points to be bred to. Nearly all dogs carry the tail to the left. Perfect bilateral symmetry in colour is rare, though there is always a tendency to it. White hair the author regards as a sign of weak- ness. In the cerebro-spinal axis, divided by deep median fissures into two corresponding halves and connected by various commissures, asymmetry is no less marked. The anterior cornu of the cord, especially in the cervical and lumbar enlargement, is somewhat larger on the right. Either side of an intact spinal cord of a decapitated frog may be well exhausted by reflex experiments, without much impairing the functions of the other side. If the stimuli increase to great strength the reflexes are diffused to more muscles on the same side before affecting those symmetrically opposite, according to Pfliiger's well-known law. As men are said to make the worst face on the side of the greatest effort in severe one-sided muscular strains, if the cord be split with proper precautions in the median plane, each side may preserve the reflexes from that side apparently intact. Setschenow did not observe in this case the double-sided anaesthesia, or reflex depression of Brown- Sequard. Cross semisection of the cord re- duces or destroys the power of voluntary motion below on the same side without much affecting it on the other, but increases sensation on the side of the lesion, and depresses it on the other side. Two opposite semisections need not be so near together to destroy the power of voluntary motion on both sides below as to destroy sensation. Whatever other inferences respecting the existence of inhibitory fibres, the course of fibres in the cord, conduction within the grey matter, &c., the many careful observa- tions of this class may justify, they have at least led to the belief that very many posterior or sensory fibres cross soon ' after entering the cellular grey, while most fibres representing the power of voluntary motion, pass down the same side. Brown- Sequard thinks the left of the cord is more concerned with nutri- tion, and the right with the functions of animal life. Of the cerebral ganglia, it has been estimated by various pains- taking observers that the entire left brain weighs more than the right ; that the specific gravity of the grey substance is greater on the left. Meynert thinks that the left 'brain has the deepest and fullest, but the right brain the most convolutions ; but some have thought that the number of folds was greatest on the left only in the occipital regions, and that there was the most white matter in the right frontal and the left occipital and cerebellar brain.