Protection against grazing animals.--Although we are considering the ways by which creeping insects are checked in their efforts to visit flowers, it seems pertinent to mention the more universal danger which comes from grazing animals. If flowers were as attractive to grazing animals as they are to insects they would be in danger of wholesale destruction. It can be observed, however, that these animals as a rule avoid the flowers of a plant, although they may strip off its leaves. It is believed that this avoidance is due to the fact that in or about the flower cluster there are usually secreted bitter, sour, or nauseous substances, which grazing animals have learned to avoid. It should not be imagined that these substances are there for that purpose, but being there the result is that the flowers are avoided. It is unknown how generally true this is, and the effectiveness of this method of protection may have been exaggerated. Those who can observe cattle, however, are in a position to test them with the flowers of the various plants they are known to eat, and determine how far they avoid them. In conclusion, it may be of interest to call attention to the great complexity of relations existing among plants and animals by repeating Darwin's famous illustration known as "Cats and Clover." In a certain district in England he observed that the clover was pollinated by the bumblebees, which had their nests in the fields. It followed, therefore, that the more the bumblebees, the more the clover. He also observed that the field mice preyed upon the young broods of the bumblebees, and, therefore, the more the field mice, the fewer the bumblebees and the less the clover. When cats were plenty and preyed upon the field mice it followed that the more the cats, the fewer the mice, the more the bumblebees, and the more the clover. Therefore, the crop of clover depended upon the presence of cats in the neighborhood. John Merle Coulter. HOW WE MAY BEST PAY THE DEBT.