Even the slight morphological differences between male and female skulls--some anthropologists deny that there are any at all--afford no more ground for conclusions in favor of the superiority of one or the other sex than the relative differences in size. Such trifling differences as do exist exhibit, as Virchow has pointed out, an approximation of men to the savage, simian and senile type, and an approach of women to the infantile type. Havelock Ellis, commenting on this difference, pertinently remarks, "It is open to a man in a Pharisaic mood to thank God that his cranial type is far removed from the infantile. It is equally open to woman in such a mood to be thankful that her cranial type does not approach the senile."[95] But much stress as has been laid on physical power, health and cranial capacity, as determining factors of intellectual capacity and sexual differences, far greater stress has been laid on conclusions deducible from the relative brain weights of different classes of people as well as of different sexes. It was assumed that by a critical study of the brain, by careful weighings of many brains of both sexes and of many races, it would be easy to secure conclusive evidence that the size and weight of the brain increase with the amount of intelligence of the individual. It was also assumed that function not only makes the organ, but also develops it. Brain became synonymous with mind. A large brain implied vigor of thought; a small brain was evidence of mental inferiority. Physiology had demonstrated unquestionably that the muscles of the body are enlarged by exercise. It was assumed by those who are wont to measure mind in terms of matter that the brain, being the organ of thought, was also developed by exercise. It was also assumed that the development of the brain was in a direct ratio to its activity. The greater its activity the greater its mass, and the greater the mass the greater the degree of intelligence. In other words, it was assumed that there was an exact and invariable proportion between weight of brain and amount of brain power. None of the theories which have already been adverted to have been so full of assumptions and prejudices or vitiated by so many fallacies and over-hasty generalizations as this. No subject has possessed a greater fascination for anthropologists, and no subject has been prolific in more diverse and conflicting conclusions. Many men of science who, in other matters, were noted for their care in weighing evidence, before formulating theories, completely lost the scientific spirit when they began to weigh brains and to draw conclusions respecting the relations of brain weight and mental power, and to establish ratios between the character of the convolutions of the organ of thought and the degree of intelligence of its possessor.