Jennings, H. S.
1906. Behavior of the Lower Organisms, pp. 366. New York.
The general chapters are particularly helpful.
Morgan, T. H.
1907. Experimental Zoölogy, pp. 454. New York.
Summaries of a variety of experimental studies.
Semper, K.
1881. Animal Life as Affected by the Natural Conditions of Existence. pp. 472. New York.
“‘The Physiology of Organisms,’ in contradistinction to the Physiology of Organs, ... [is] that branch of animal biology which regards the species of animals as actualities and investigates the reciprocal relations which adjust the balance between the existence of any species and the natural, external conditions of its existence, in the widest sense of the term.” p. 33.
Jensen, P.