50 



THE HISTORY OF ECOLOGY 



"Color and Pattern in Animals." This was a 

 useful book which, in the second decade, 

 emphasized the close connection between 

 ecology and organic evolution. 



These, then, are some of the books that 

 ecologists were reading during the decade 

 1911 to 1920. Of course there were others, 

 but the ones mentioned should suffice as a 

 sample. It is our task now to survey briefly 

 certain specific papers as we did in the 

 preceding section. We use the same head- 

 ings as before: viz., natural history; re- 

 sponse, developmental and toleration physi- 

 ology; hydrobiology; succession; and syne- 

 cology. In addition, we shall have a word 

 to say about the growth of quantitative 

 methods. 



Since ecology is always based in the 

 final analysis on natural history, we find 

 that subject constantly present and to be 

 accounted for. During the decade 1911 to 

 1920 many first-rate natural history papers 

 were published. These ranged from such 

 popularized reports as Brunner's Tracks and 

 Tracking (1912), which was an "illustrated 

 guide for the identification of mammal and 

 bird tracks or footprints," to such compre- 

 hensive studies as those of Herrick (1911), 

 Belding and Lane (1911), Needham 

 (1920), and Pearse and Achtenberg 

 (1920). 



Response physiology was an active phase 

 of ecology during the second decade. While 

 the investigations ranged considerably in 

 type, there was a drive towards expressing 

 animal behavior in as precise terms as 

 possible. Frequently, this led the study into 

 experimentation as distinguished from 

 uncontrolled observation. The ecological 

 contributions were made largely through 

 knowledge acquired of the way a single 

 environmental factor induced an organismic 

 response. Review of several studies will 

 clarify these points. 



A paper that was interesting from both 

 the behavioristic and ecological points of 

 view was that of Severin and Severin 

 (1911) on death feigning in two aquatic 

 bugs, Belostoma and Nepa. These investi- 

 gators were concerned with three aspects of 

 the problem: careful description of the 

 death-feigning attitudes, environmental fac- 

 tors inducing death feigning, and the 

 possible significance of this response when 

 expressed in terms of survival value. For 

 example, it was found that while Belostoma 

 assumed either of two attitudes, Nepa 



"froze" in the position it held at the time 

 the stimulus was presented. The authors 

 noted that dryness decreases and moisture 

 increases the duration of the death feint in 

 Belostoma and that high air temperature 

 shortens the duration for both species. Their 

 general conclusion about the character of 

 the response is that "... the death feint 

 in arthropods is simply a non-intelligent 

 instinctive act" (p. 39). 



Dawson (1911), in "The Biology of 

 Physa," approached this topic with a be- 

 havior emphasis, but reported much that 

 was ecological, particularly in two sections 

 of the paper: "The Relation of Physa to Its 

 Natural Environment; Including a Compre- 

 hensive Analysis of the Habits of Physa in 

 the Ann Arbor Region," and "The Food and 

 Feeding Activities of Physa." The section 

 on "Psychic Phenomena" contains an inter- 

 esting and ecologically pertinent discussion 

 of the "source of stimuli received by Physa 

 in field habitats." Present day ecological 

 work would profit by careful analyses of 

 the latter type! In 1911 S. O. Mast pub- 

 lished Light and the Behavior of Organisms. 

 This was a valuable stimulus to compara- 

 tive psychology, and it also synthesized 

 much that was instiTictive to the ecologist. 

 Also during the decade Jacques Loeb 

 (1918) published his well-known and 

 polemic book on a mechanistic interpreta- 

 tion of behavior. Forced Movements, Tro- 

 pisms and Animal Conduct. 



Developmental physiology underwent 

 more specialization during the decade. It 

 also linked itself closely with embryology. 

 Nevertheless, many papers were published 

 that contributed to the growth of ecology. 

 LeFevre and Curtis (1912) reported at 

 length on the reproduction of fresh-water 

 mussels. Much of their work had distinct 

 ecological and parasitological emphasis. 

 Thus they discussed the development of the 

 embryonic mussels in the gills ("marsupi- 

 um") of the mother. They studied breeding 

 seasons and recognized "summer breeders" 

 and "winter breeders." They described the 

 development and behavior of the glochidia, 

 including the parasitization of the fish by 

 these larvae. Finally, they dealt with the 

 establishment of the young mussel on the 

 bottom and its subsequent maturation. 



During this decade there was a growing 

 focus, later to reach fuller clarity, on the 

 effect of the physical environment upon 

 developmental rates. Usually, either tern- 



