Granting the local origin of pueblo architecture it would appear at first sight that a very long period of time must have elapsed between the erection of the first rude rooms and the building of the many-storied pueblos, yet the evidence now available--that derived from the ruins themselves, documentary evidence, and traditions--all suggest that such was not necessarily the case. As a record of events, or rather of a sequence of events, tradition, when unsupported, has practically no value; but as a picture of life and of the conditions under which a people lived it is very instructive and full of suggestions, which, when followed out, often lead to the uncovering of valuable evidence. The traditions of the pueblo tribes record a great number of movements or migrations from place to place, the statements being more or less obscured by mythologic details and accounts of magic or miraculous occurrences. When numbers of such movements are recorded, it is safe to infer that the conditions dictating the occupancy of sites were unstable or even that the tribes were in a state of slow migration. When this inference is supported by other evidence, it becomes much stronger, and when the supporting evidence becomes more abundant, with no discordant elements, the statement may be accepted as proved until disproved. The evident inferiority of the modern pueblos to some of the old ruins has been urged as an argument against their connection. While degeneration in culture is yet to be proved, degeneration of some particular art under adverse conditions, such as war, continued famine, or pestilence, is not an uncommon incident in history, and it can be shown that under the peculiar conditions which prevailed in the pueblo country such degeneration would naturally take place. One of the peculiarities of pueblo architecture is that its results were obtained always by the employment of the material immediately at hand. In the whole pueblo region no instance is known where the material (other than timber) was transported to any distance; on the contrary, it was usually obtained within a few feet of the site where it was used. Hence, it comes about that difference in character of masonry is often only a difference in material. Starting with a tribe or several tribes of plains Indians, who came into the pueblo country, we should probably see them at first building houses such as they were accustomed to build--round huts of skin or brush, perhaps partly covered with earth, such as were found all over middle and eastern United States. Supposing the tribe to have been not very warlike in character and subsisting principally by horticulture, these settlements would necessarily be confined to the vicinity of springs and to little valleys where the crops could be grown. The general character of the country is arid in the extreme, and only in favored spots is horticulture possible. In a very short time these people would be forced to the use of stone for