[190] Nature of Animal Intelligence and Methods of Investigating It, Psychological Review, vol. 10, pp. 262-274, 1897.
[191] An Experimental Study of the Mental Processes of the Rat, American Journal of Psychology, vol. 11, pp. 135-164; vol. 12, pp. 206-210, 1900-1901.
[192] Mental Life of Rhesus Monkeys in Captivity, American Journal of Psychology, vol. 13, pp. 97-148, 180-210, 1902.
[193] A Preliminary Study of the Psychology of the English Sparrow, American Journal of Psychology, vol. 15, pp. 313-346, 1904.
[194] For a more complete report of this special part III, see the writer's paper, Respiration and Emotion in Pigeons, Journal of Comparative Neurology and Psychology, vol. 15, pp. 494-513, 1905.
[195] If shallowing accompanies quickening, the respiratory activity may be no greater than before; but since depth alterations were seldom observed in these trials after the first day of experimentation, the rise in rate may be taken as a fair measure of the influence of the stimulus.
[196] P. Zoneff und E. Meumann: op. cit., pp. 57, 58.
[197] R. MacDougall: The Physical Characteristics of Attention, Psychological Review, vol. 3, pp. 162, 176, 177, 1896.
[198] Thorndike: op. cit., pp. 13-15.
[199] Small: op. cit., vol. 12, pp. 236, 237.