The flame of life is easily blown out in certain forms, and is very tenacious in others. How unequally the power to resist cold, for instance, seems to be distributed among plants and trees, and probably among animals! One spring an unseasonable cold snap in May (mercury 28) killed or withered about one per cent of the leaves on the lilacs, and one tenth of one per cent of the leaves of our crab-apple tree. In the woods around Slabsides I observed that nearly half the plants of Solomon's-seal (_Polygonatum_) and false Solomon's-seal (_Smilacina_) were withered. The vital power, the power to live, seems stronger in some plants than in others of the same kind. I suppose this law holds throughout animate nature. When a strain of any kind comes, these weaker ones drop out. In reading the stories of Arctic explorers, I see this process going on among their dog-teams: some have greater power of endurance than others. A few are constantly dropping out or falling by the wayside. With an army on a forced march the same thing happens. In the struggle for existence the weak go to the wall. Of course the struggle among animals is at least a toughening process. It seems as if the old Indian legend, that the strength of the foe overcome passes into the victor, were true. But how a new species could arrive as the result of such struggle is past finding out. Variation with all forms of life is more or less constant, but it is around a given mean. Only those acquired characters are transmitted that arise from the needs of the organism.