d not alone suffice to produce this
architectural type. In order to develop the results found, another
element was necessary. This element was the necessity for defense. The
pueblo population was probably subjected to the more or less continuous
influence of this defensive motive throughout the period of their
occupation of this territory. A strong independent race of people, who
had to fear no invasion by stronger foes, would necessarily have been
influenced more by the physical environment and would have progressed
further in the art of building, but the motive for building rectangular
rooms--the initial point of departure in the development of pueblo
architecture--would not have been brought into action. The crowding of
many habitations upon a small cliff ledge or other restricted site,
resulting in the rectangular form of rooms, was most likely due to the
conditions imposed by this necessity for defense.

[Illustration: Plate CXI. Zuni eagle-cage.]

The general outlines of the development of this architecture wherein the
ancient builders were stimulated to the best use of the exceptional
materials about them, both by the difficult conditions of their
semi-desert environment and by constant necessity for protection against
their neighbors, can be traced in its various stages of growth from the
primitive conical lodge to its culmination in the large communal village
of many-storied terraced buildings which we find to have been in use at
the time of the Spanish discovery, and which still survives in Zuni,
perhaps its most striking modern example. Yet the various steps have
resulted from a simple and direct use of the material immediately at
hand, while methods gradually improved as frequent experiments taught
the builders more fully to utilize local facilities. In all cases the
material was derived from the nearest available source, and often
variations in the quality of the finished work are due to variations in
the quality of the stone near by. The results accomplished attest the
patient and persistent industry of the ancient builders, but the work
does not display great skill in construction or in preparation of
material. The same desert environment that furnished such an abundance
of material for the ancient builders, also, from its difficult and
inhospitable character and the constant variations in the water supply,
compelled the frequent employment of this material. This was an
important factor in bringing abo