Have you ever tried to crawl up on a bunch of wild ducks, or sat behind a blind while your wooden decoys were spread on the water all around you? If you have done either, I know you will agree with me when I say the wild duck is a very smart fellow indeed. His eye is keen, he is full of sense, and very hard to fool. Now his cousin, the tame duck, is next door to an idiot. He cannot hide himself or protect himself in any way. Strangely enough, too, while the wild duck finds one wife and one family quite all he can attend to, the big, hulking tame duck is a regular Mormon, and prefers a dozen wives, and neglects his children sadly. It is not hard to guess why these two birds are so different. The tame duck is only a wild duck domesticated, that is, put in such a position that he could not continue to live the natural sort of life that was best for him, the life of continuous struggle. He is, in short, a degenerate wild duck; his wings are not so broad or so strong, the muscles of his breast have grown puny and shrunken; he does not even want to fly far north in spring or far south in winter. He is content with his farm-yard and puddle. He has stopped _trying_, and so has stopped _growing_ too. One more instance I will give you, boys, of the important place this law of struggle plays in the lives of the very beasts. I was visiting some time ago the museum in one of our universities. One of the professors was with me, and we came to a case full of plaster casts of brains, the brains of animals. While looking at these you could, of course, easily compare their size and character, and form some opinion of the intelligence of the animal itself. The professor pointed out to me one very interesting brain cast. It was taken from the head of a rhinoceros that had lived very long ago--lived at the same time as mammoths and other antiquated animals. It was quite a large and well-developed brain. We next went to another case and took out the cast of a common rhinoceros, such a one as lived in our own times, and it was very evident that the present-day rhino was not nearly so large or intelligent as his progenitor of long ago. This seemed at first very strange; for why should the rhino's brain have degenerated while they are still struggling forward in the march of life? The answer is to be found in the sort of battle they have to fight. When the antediluvian rhino lived, the world was peopled with terrible monsters, brutes of great strength and savagery. With these he had no easy time of it. He had to match himself against them. Great strength alone was not enough; he needed cunning as well. Struggle he must, and struggle hard or go under; and he survived because he did struggle hard and did not go under. When, however, most of the monstrous forms of life had gradually passed away, the rhinoceros had no enemy he stood much in dread of. The milder animals of a later day get out of his way. There is nothing to be gained by contending with him.