attitude. The first turn, particularly when the lesion is old, is slower and less regular; the second is rapid and spasmodic. The first is the consequence of the lesion, the second is the consequence of the regular action of all the nervous centres; and, the better to express this thought,

we may say that, in an animal from which have been taken only the cerebral lobes, we might obtain a movement of rotation if, as soon as the animal is on his fore-feet, we turn him on his back; external interference would replace in this case the action produced by lesion of the pons Varolii.