We may know that by exercising a certain organ we are building up a certain part of the brain. For example, the man who has cultivated his hearing until he can hear sounds inaudible to ordinary men, has made for himself more brain-cells in the hearing area. If he has cultivated his sight assiduously, he has created more visual cells. If his touch has been cultivated, his brain has received new touch sensation-cells. And Professor Gates asserts that his mental ability has been thereby increased. You will be interested in hearing of his experiments with animals and what he has learned therefrom. He says he has demonstrated that it is possible to give to an animal or a human being more brains, and consequently a better use of the mental faculties. During twelve months, for five or six hours a day, he trained dogs to discriminate colors. He placed several hundred tin pans, painted different tints, in the yard with the dogs. At one time he put their food under pans of a certain tint. When they had learned to go at once to these pans for their food, he changed the color. Again he arranged it so that they would receive an electric shock if they touched pans of any color save the particular one. They soon learned to avoid all the pans except those of this tint. So, by many different methods, he trained them to recognize shades and tints until they could discriminate between seven shades of red and as many shades of green, and in many ways they manifested more mental ability than any untrained dog. While these dogs were being trained, another group of dogs were being deprived of the use of sight by being kept in a darkened room. At the end of the year both groups of dogs were killed and their brains dissected. He found that the dogs kept in the darkness had less than the usual number of cells in the seeing areas, and the cells were smaller, while the dogs which had been trained to discriminate between tints and shades of color many times a day had a far greater number of larger and more complex brain-cells in the seeing areas than any dog of that age and species ever had before. "Therefore," says Professor Gates, "mind activity creates organic structure." Prof. Gates discovered other things of equal importance. He carried his observations to successive generations, and found that the fifth generation was born with a far greater number of brain-cells than could be found in animals not descended from trained ancestors. This is not only interesting, but of value. You will remember, in our talk concerning your value, we spoke of your value to the race, and learned that in cultivating yourself in any direction you were adding to the welfare of future generations. That was only a general statement, and now you can see how it can be. You see that if you can make more brains for yourself you are also making more brains for your posterity. Or if you fail to make brains for yourself, posterity will in like degree be defrauded.