I do not need to extend illustrations which abound in the insect world, especially among the ants, which furnish cases of coadaptation that cannot be transmitted, as they do not propagate, so I will not mention them here. Now, if acquired characters _are not_ transmitted to offspring, how should these facts affect our methods of educating children? One advantage will be evident, I think, to all. Erroneous systems of training, which do not injure the health, will not appear through heredity in the offspring of parents thus wrongly trained, except as a result of environment. That is to say, the injury does not become congenital--will not be in the blood--and, consequently, it will be less difficult to eradicate it and to introduce better systems. This may be considered an advantage. But it is not all. If heredity takes place only through the germ-plasm, then it seems to me that whatever promotes a knowledge of how to maintain it in a high degree of health, and how to favor more perfectly natural selection, are subjects with which our educators may busy themselves far more than they do. That is to say, the study of biology, of life--of the laws of human growth and development, and of evolution, will become, more and more, important factors in our school curriculum. We can hardly imagine how much our common every-day life has been aided by even the slight knowledge of mathematics gained by an acquaintance with addition, subtraction, multiplication and division. By it we are able to keep our little accounts correctly, and neither cheat our creditors nor be cheated by them. Could we not by a knowledge of the laws of evolution, and also the laws of growth and development, keep our larger account with nature in a far better condition? Could we not keep ourselves from being cheated out of our health and happiness, and also do something to put an end to physical, intellectual and moral deterioration which threatens so many families and even races? It seems to me that the time is not far distant when these studies will be quite as much attended to as the not unimportant ones of arithmetic and grammar.