The statements contradictory to those of Kollmann are probably to be explained by the brevity of the observations. Virchow ("Correspondenzblatt," S. 135), in his remarks upon this case, says: "I am convinced that every one who observes the microcephalic child will find that psychologically it has nothing whatever of the ape. All the positive faculties and qualities of the ape are wanting here; there is nothing of the psychology of the ape, but only the psychology of an imperfectly developed and deficient little child. Every characteristic is human; every single trait. I had the girl in my room a few months since, for hours together, and occupied myself with her; I never observed anything in her that reminds me even remotely of the psychological conditions of apes. She is a human being, in a low stage of development, but in no way deviating from the nature of humanity." From these reports it is plain to be seen that for all mental development an hereditary physical growth of the cerebrum is indispensable. If the sensuous impressions experienced anew in each case by each human being, and the original movements, were sufficient without the development of the cerebral convolutions and of the gray cortex, then these microcephalous beings, upon whom the same impressions operated as upon other new-born children, must have had better brains and must have learned more. But the brain, notwithstanding the peripheral impressions received in seeing, hearing, and feeling, could not grow, and so the rudimentary human child could not learn anything, and could not even form the ideas requisite for articulate voluntary movement, or combine these ideas. Only the motor centers of lower rank could be developed. In peculiar contrast with these cases of genuine microcephaly stands the exceedingly remarkable case, observed by Dr. Rudolf Krause (Hamburg), of a boy whose brain is not at all morbidly affected or abnormally small, but exhibits decidedly the type of the brain of the ape. The discoverer reported upon it to the Anthropological Society ("Correspondenzblatt a.a. O., S. 132-135) the following facts among others: