for inquiry, upon which no agreement has apparently been reached, how it came to pass that man has virtually lost his hairy coat, and in regard to the palms and soles of animals, what may be the reason that so few have any hair on them, and why man has no sebaceous glands, but has very numerous sweat-glands in these regions. [63] _The Sense of Touch in Mammals and Birds._ A. & C. Black, 1907. This is all of great interest, and possibly some day the Mendelians will solve for us the mysteries thereof. But here I need only ask how it would have been possible for hairs to grow, or, if growing, not to be promptly worn away on a surface used by animals from monotreme to man for walking-pads, and by most of them also for grasping and discrimination between objects as well. We are so familiar with the thickening of the skin on the hands of manual workers and on the feet of those who walk much, to say nothing of what we call a “corn,” from pressure of tight boots, that we are in danger of forgetting that the protecting skin over the hands and feet of animals was of necessity adjusted in a crude way to the measure and kind of walking in past ages and in all levels of life, and that it is maintained in that adjusted condition by the use, or disuse, of each life. Another familiar example is that of knee-pads, as in the gnu and other ungulates. Some such process it is legitimate to assume whether it be reckoned backwards to monotremes or later levels of life-forms. We see then before our eyes how this living tissue becomes adapted in varied ways by response to the stimuli of friction and pressure, and the modifications thus slowly effected must, one would suppose, be transmitted to offspring ultimately from the original groups with which the process began, when by frequent repetition small changes of structure have arisen at last. I acknowledge the limited force of the answer, that this picture involves the continuance in each succeeding generation of the stimuli which initiated the changes, but the fact remains that _ex hypothesi_ the changes are there, written in tablets of animal tissue, and that the making-up of an organism in course of many ages is not and cannot be conceived as being governed alone by the “tyranny,” even in the _good_ Greek sense of that word, of rigid unit-characters.