of the notochord in some of the invertebrates present phenomena
far more wonderful per capita than many a brain produces.
Interesting books have been written, and more will be written
hereafter, on the minds and doings of ants, bees, wasps, spiders
and other insects.

Consider the ways and means of the ant-lion of the East, and the
trap-door spider of the western desert regions. As one object
lesson from the insect world, I will flash upon the screen, for a
moment only, the trap-door spider. This wonderful insect personage
has been exhaustively studied by Mr. Raymond L. Ditmars, in the
development of a series of moving pictures, and at my request he
has contributed the following graphic description of this
spider's wonderful work.

"The trap-door spiders, inhabiting the warmer portions of both the
Old and New Worlds, dig a deep tunnel in the soil, line this with
a silken wallpaper, then construct a hinged door at the top so
perfectly fitted and camouflaged with soil, that when it is closed
there is no indication of the burrow. Moreover, the inside portion
of the door of some species is so constructed that it may be
"latched," there being two holes near the edge, precisely placed
where the curved fangs may be inserted and the door held firmly
closed. Also, the trap-door of a number of species is so designed
as to be absolutely rain-proof, being bevelled and as accurately
fitting a corresponding bevel of the tube as the setting of a
compression valve of a gasolene engine.

[Illustration: THE TRAP-DOOR
SPIDER'S DOOR AND BURROW By R. L. Ditmars 1. The door closed. Its