But though man became almost emancipated from the direct servitude of natural selection, he still is, and always will be, subject to the law of heredity. Man is made up of a group of innate characters inherited from a very mixed ancestry, these characters, being innate, are transmissible to his offspring, but such characters as are acquired by the parent through the direct influence of education or other environment, not being innate are not transmissible to his children. But in so far as a new development of latent and innate characters, through the influence of the environment, may help or hinder certain types in propagating themselves, the race may, perhaps, be modified through such influence by the process of gradual elimination of the types that lack the characters that prove to be of survival value in a particular locality. This we may suppose might happen where a number of Europeans, composed half of blondes and half of brunettes, come to live in a tropical country, if it be proved that the comparative darkness of the brunettes afford them better protection against inimical light and heat than the fair skin of the blondes, so that the former would on the average, enjoy better health and live longer, and therefore have more children than the latter, whereby, in course of time, the appearance of these people would be modified in respect of the general complexion of their skin. This, it is easy to see, would not mean the acquisition of a new and heritable means of protection, but only a development in each individual of an already present innate character that happened to be well fitted for survival in a certain climatic zone. In order, therefore, to obtain any direct modification of the race in the way of mental improvement the physical effect of education must be such as to ensure longer life and with it, the concomitant chance of greater fertility for those who are educated against those who are not, so that the latter would tend to die out while the former would continue to increase their numbers. In other words, education must prove to be of survival value. Seeing that where education has increased most the birth-rate has tended to decrease it seems clear that we cannot regard continuous mental training as a favourable factor in the competition of propagation of human varieties.