[22] Dr. Hammond, Professor of Diseases of the Nervous System at Bellevue College, New York, has published some interesting statistics in reference to the relative weight of the brain, as compared with that of the body, in various classes of vertebrate animals, by which he shows that there is no definite relation between the intelligence of animals and the absolute or relative size of the brain. Thus, he says, "the canary bird and the Arctic sparrow have brains proportionately larger than those of any other known animals, including man, and yet no one will contend that these animals stand at the top of the scale of mental development. Man, who certainly stands at the head of the class of mammals, and of all other animals, so far as mind is concerned, rarely has a brain more than one-fiftieth the weight of the body, a proportion which is much greater in several other mammals, and is, as we have seen, exceeded by many of the smaller birds."
[25] At a meeting of the Medico-Psychological Society of Paris, my friend M. Auguste Voisin exhibited plates of the brains of idiots who had only begun to speak at the age of from three to five years, in which the frontal and first parietal convolutions were rectilinear without secondary folds, resembling the fœtal condition of the convolutions at the sixth month of intra-uterine life.
[26] The imagination of certain psychologists seems to have gone rampant upon this subject; one writer, M. Moreau, of Tours, maintained that genius was a nervous disease--"le génie est une névrose"; and in order that there may be no mistake about his meaning, he adds that "the constitution of many men of genius is in reality the same as that of idiots!" M. Moreau's doctrine may thus be summarised in his own words--"Les dispositions d'esprit qui font qu'un homme se distingue des autres hommes par l'originalité de ses pensées et de ses conceptions, par son excentricité on l'énergie de ses facultés affectives, par la transcendance de ses facultés intellectuelles, prennent leur source dans les mêmes conditions organiques que les divers troubles moraux, dont _la folie et l'idiotie_ sont l'expression la plus complète."
[27] Le Cerveau et la Pensée, par Paul Janet Membre de l'Institut. Paris, 1867, p. 58. This learned treatise contains an immense deal of information in reference to the mysterious connection between matter and mind, and I have found it of great service to me in my psychological researches.