It might seem that the air in a cave constantly occupied would grow stale and close; while smoke from the fires would in time become annoying. But Indians used for fuel only dry wood and bark, the smoke from which would be a negligible factor. The varying pressure of the atmosphere outside creates a current of air in or out which is usually imperceptible but which penetrates to the deepest recesses and insures ventilation.
In view of the very primitive conditions under which cave dwellers lived, as denoted by the artificial objects which they left, and the low mentality indicated by the skulls, Mr. W.H. Holmes suggests that a careful and extended study of these abodes may disclose a culture lower than that prevailing among out-door dwellers in the same localities. As no effort would be required to secure warmth and shelter, and as food was