Among many scientists to-day it is supposed to be crude to speak of purpose in nature, and there is reason for their attitude. But the statement that there is no such plan conveys to the ordinary thinker a meaning that is far more erroneous than could possibly exist in his mind should he believe implicitly in design and purpose. As between design in the universe in the usual sense of the word, and a purely accidental connection of events in the universe, there can be no doubt as to the choice. The truth is far better expressed by the word design than by the chaos which is the alternative idea in the average mind. In these later years we have come to use a different word. We now conjure in such connection with the word adaptation. In every animal and every plant the trained eye sees unending examples of adaptation; that is, of a fittedness to the work it has to do. The modern scientist feels sure not only that the animal is fitted to his work, but that he has been so fitted by the work; that the very use he makes of his organs has determined their structure. This work has decided that the structure which he has is the structure that shall survive and shall produce other structures like itself. Adaptation therefore does not simply express the idea that the animal is adjusted to its surroundings, but it further suggests that the animal by gradual process has become thus adjusted. The word adaptation applies not simply to the result, but also to the process. The scientist does not consider the animal a final and complete result. He thinks it still in a state of flux, and so long as its line lasts it will be in a state of flux. Change is about it on every side, and it must adapt itself to this change or it will pass away. It may adjust itself, as has been previously stated, by moving to another environment in which it feels more at home, but unless it does this, if there come much change in its present surroundings, it must either meet the difficulty by altering itself, or it must give up the struggle. The alteration is unconscious so far as the animal is concerned. It is seriously to be doubted whether there is any recognition of the process on the part of any animal excepting man. But though the process be unconscious, it is none the less there. Slowly and gradually the animal and the environment are becoming adjusted to each other. While it is exceedingly difficult to lay our hands on any animal which is at present visibly changing its structure, it is not hard to find closely related animals. These are nearly alike in structure in most respects. In a few points, however, they may differ materially, and these points are often directly concerned with different habits of life. Considered in this aspect, these adaptations of a single organ separately examined form an excellent argument in favor of that gradual alteration of the entire organism which evolution suggests.