Even tribes on a rather low stage have no doubt noticed the most conspicuous among the stellar bodies. The attitude of the Australian aborigines is significant in this connection. According to Spencer and Gillen they possess legends about the Moon, which is male, about the Sun and Venus, about the pernicious Magellanic clouds, and about the Pleiades, who, like the Sun and Venus, are considered female. Eclipses have, as is natural, attracted the greatest attention. While these primitive men indulge in an incredible number of religious ceremonies pertaining to conditions of their daily life, none of these exercises are devoted to the stars, if we except stone throwing against the Sun during eclipses. Even this treatment is left with considerable serenity of mind for the medicine-men to perform. It is very significant that all stellar bodies are of earthly origin, that the Moon is of male gender while the Sun, Venus, and the Pleiades are female, which indicates that the Moon is considered of greatest distinction. They count time according to “sleeps,” _i. e._ the number of times they have slept, or according to moons; longer periods according to seasons; they have names for summer and winter. They can count to five, or perhaps rather to four, as the term five also means “many.” Ideas of power centred in the stellar bodies are evidently absent and therefore also religious ceremonies pertaining thereto. A few tales exist relating to the stars as to other objects within their observation. Thus conditions would undoubtedly have remained but for the high value which the want of a chronometry gave to the regularly changing light of the stellar bodies. The difference between day and night is of such a deeply fundamental importance that it has left its stamp on the whole organic nature on the surface of the Earth. Plants entirely change their life processes in the course of twenty-four hours; during the day they add to their growth under the stimulus of light; during the night they partly expend the strength gathered in daytime. This cycle is so regular that it functions automatically. The prominent botanist, Pfeffer, has experimented with a Mimosa, which, as is well known, unfolds its leaves during the day but curls them during the night. If left in a dark room any arbitrary day, it nevertheless uncurls its leaves. By means of electric light Pfeffer changed night into day for the plant kept in the dark room. It took considerable time before the plant adjusted itself to the new conditions so that it unfolded its leaves to the influence of the electric light. Animals behave similarly. The night and day period is instilled in their blood. In a certain sense they possess an instinctive chronometry.