smaller cage. This was only some six feet square, as tall as the larger, and built on the end of this larger one. Like the large cage, the floor of this was on a level with the windowsill. My chief difficulty was with the temperature. With the direct rays of the sun coming in through the one window and the fact that but one end of this cage was of wire, the heat became too great during the middle of the day even in midwinter. The results of this series contribute little positive with reference to imitation, but the negative results obtained are of suggestive value and interesting relations of the two species have been brought out.
As the reader may gather from the accompanying figure, Fig 11, the food-box here used is identical in principle with that which I first used. Fig. 1 Am. Jour. Psy., Vol. XV, p. 319. Reference to Table IV will show that the female Cowbird first opened the door. In the next trial, though she made nine efforts, the female English Sparrow was successful. She did not pull the loop or strike at the free end of the latch, but pulled at the wire hinge which fastened this latch to the door. She drove all other birds away just prior to opening the door. It should be noted that after the door was opened in the first test the Sparrows did not enter, but ate the food thrown out through and under the wire by the Cowbirds. The Sparrow's method of opening the door cannot be called an imitation of that used by the Cowbird.
During the third test and some of the succeeding ones there were pitched battles between the Sparrows and the male Cow-
_Fig_11.jpg)
Fig. 11
Female English Sparrow opening door by pecking at the knot on the string where it passes through the latch. She repeatedly drove all the others away from the door in order to open it.
