In all probability the slate pit-dwellings were originally constructed as places of refuge from the warlike, predatory tribes of the North; and judging from the number of enemy skulls in Paiwan villages, these slate refuges were effective. Curiously enough, however, the “bachelor-houses,” in which the young unmarried men live, are built of wood, on high piles, or stakes. The mode of entry to these bachelor-houses has already been described.[88] The young men are supposed to have at least one of their number constantly on guard, in order to detect the possible approach of an enemy. In such an event a warning is given, when the women and children retreat within the slate houses. The married men also repair to their houses, but only long enough to collect their arms; when, having done so, they sally forth to join the bachelors in an attack upon the enemy. Only, as a last resort, when hard pressed by the enemy, do the men--in such an emergency, bachelors as well as married men--retreat within the slate huts and, firing through doors and windows, attempt to keep the enemy at bay. Among the Paiwan the house of a chief has usually three windows, and the house of a commoner always one, sometimes two; consequently this mode of “aggressive defence” is often successful. Among the peace-loving Yami--the inhabitants of the tiny island of Botel Tobago--slate houses are not found. Family houses, as well as the “long-houses” of the bachelors, are of the “pile-dwelling” variety. [Illustration: PAIWAN VILLAGE OF SLATE. _The houses are of the pit-dwelling variety; a larger portion of each house is below ground._] However the dwelling-houses of the different tribes may vary, the millet granaries of all the tribes seem built after an identical pattern. There is in each village of every tribe a communal granary--a hut, built sometimes of wood, sometimes of bamboo, but always supported on pillars, some five or six feet above the ground. Near the top of each of the four pillars is a round piece of wood (among the Paiwan slate is sometimes substituted for wood) supposed to prevent rats and mice “and such small deer” from entering the granary.[89] This _rokko_, as the Taiyal call the “rat-preventer” (to translate literally), is found in the granaries and store-houses of many of the Oceanic peoples--both in the Lu-chu Islands and in certain parts of Melanesia; a coincidence which is not surprising. It is, however, rather surprising to find the same device used among the Ainu of Hokkaido and Saghalien. This fact tends rather to upset one’s theory that the culture of the Formosan aborigines is of purely Indonesian origin--unless perhaps one accepts the hypothesis that in this instance the Ainu have borrowed a custom from their southern neighbours; or again, unless it be a case of “independent origin,” a discussion of the pros and cons regarding which theory cannot be attempted here.