One important effect of the glacial chill needs to be adverted to. The severity of the weather was not the only thing to be provided against. The discovery of fire and the invention of clothing and habitation were not enough to insure man's preservation. For the severe cold must have greatly changed the conditions of the food supply, and the man of the period found it a difficult matter to obtain the first necessaries of life. The easy-going man of the earlier age, living amid an abundance of fruits and vegetables and surrounded by numbers of game animals, or dwelling beside streams which were filled with easily taken fish, probably found the question of subsistence one of minor importance. The coming on of the Glacial Age made this question one of major importance. The supply of fruits and vegetable substances was greatly decreased by the biting chill, and the number of food animals was correspondingly reduced; while through much of the year the effects of frost drove the fish from the streams, and cut off effectually this source of food. Man was brought into a situation in which only the most active exertion of his powers of thought could preserve him from annihilation. He now found the exercise of the art of hunting more difficult than ever before, one that needed a new development of courage, cunning, alertness, and endurance, the scarcity of animals obliging him to make long journeys and attack the strongest creatures. Whether or not he possessed the poisoned arrow, which the Pygmies now find so effective, cannot be said, but in all probability he was forced to invent new and more destructive weapons, a necessity that gave fresh exercise to his powers of invention. So far as our actual knowledge goes, the art of chipping stones into weapons and implements was not possessed before this period, and it may have been a result of the severe exigencies of the situation and the mental stimulation thence resulting. This art is not possessed by any of the Pygmies, the nearest approach to it being the splitting of stone by fire and using the splinters as weapons. Very likely preglacial man was similarly destitute of this art.