Obermaier(25) has given careful study to the vicissitudes of cave life in Mousterian times. Long before these caves were inhabited by man, they served as lairs or refuges for the cave-bear and cave-hyæna, as well as for many birds of prey. For example, the cave of Echenoz-la-Moline, on the upper waters of the Saône, contained the remains of over eight hundred skeletons of the cave-bear, and no doubt it cost the Neanderthals many a hard-fought battle before the beasts were driven out and man possessed himself of the grotto. Fire may have been the means employed. It has been questioned whether the caves were not unhealthy dwelling-places, but it must be remembered that, except in certain caverns which had natural openings through the roof for the exit of smoke, there was no true cave life, but rather a grotto life, which centred around the entrance of the cave. The smallest cave, this author observes, was considerably larger and better ventilated than the small, smoky cabins of some of the European peasants, or the snow huts of the Eskimo. The most serious obstacle was the prevailing dampness, which varied periodically in the caverns, so that dry seasons were succeeded by abundant moisture seeping through the limestone roof and down the side walls. At such times the caverns were probably uninhabitable, and in the bones of both men and beasts many instances have been observed of diseased swellings and of inflammation of the vertebræ, such as are caused by extreme dampness. The compensating advantages were the shelter offered from the rain and cold, a constant temperature at moderate distances from the entrance, and also the fact that the caves were very easily defensible, because the entrance was generally small and the approach often steep and difficult; a high stone wall across the opening would have made the defense still easier, and a flaming firebrand would have prevented the approach of bears and other beasts of prey. On account of this shelter from the weather and wild beasts the grottos and the larger openings of the caverns were certainly crowded with the Mousterian flint workers during the inclement seasons of the year. Yet the greater part of the life of the Neanderthals was undoubtedly passed in the open and in the chase. Throughout Mousterian times the commonest game consisted of the wild horse, wild ox, and reindeer. Both flesh and pelts were utilized, and the marrow was sought by splitting all the larger bones. Thus, frequently we find in the hearths the remains of the mammoth, the woolly rhinoceros, the giant deer, the cave-bear, and the brown bear. From these beasts of prey the Neanderthal hunters obtained pelts and perhaps also fat for torches used to light the caverns; there is no proof of the invention of the lamp at this period.