In a paper on “The Physiology of Mind in the Lower Animals,” in the Journal of Mental Science for April, 1871 (p. 79), I endeavoured to prove that other animals than man possess the same kind of moral and intellectual endowments and apply them to the same practical purposes that he does. The object of the present paper is to show that Mind in the lower animals, or certain of them, is liable to be affected by the same causes of disturbance—is subject to the same forms of defect or disorder—as in man.