INTRODUCTION 



(1937), which shows that "physical char- 

 acters are least affected by the environment, 

 that intelligence is affected more; educa- 

 tional achievement still more; and person- 

 ality or temperament, if our tests are to be 

 rehed upon, the most." 



Reasons for the slow development of 

 ecology can be foimd in the general state 

 of nonecological science, in the relative ina- 

 bihty of ecologists to work with intellectual 

 and physical tools of precision, and espe- 

 cially in the scope and iimate complexity of 

 the subject. 



There are few good reasons other than 

 the convenience ot authors and readers for 

 not treating ecology as a whole. Plant ecol- 

 ogists can make a strong case for focussing 

 on plant relations and largely neglecting 

 animal hfe, since the plants are primary 

 producers and play a highly important role 

 in providing shelter for many types of ani- 

 mals. Even so, the neglect of animal 

 activities omits or minimizes such phenom- 

 ena as grazing and browsing, working of 

 the soil, seed scattering, and the pollination 

 of many important flowering plants. Stu- 

 dents of animal ecology must give due 

 attention to plants if for no other reason 

 than that animals Uve in an environment 

 largely conditioned and controlled by the 

 plant matrix. Acknowledging the failure of 

 the present work to develop a unified ecol- 

 ogy, we fully recognize the need for a 

 future work on the Principles of Ecology 

 which will make the logical synthesis of 

 the two fields. 



Plant ecology presents two aspects, vege- 

 tational and floristic. Animal ecology largely 

 lacks the vegetational phase so far as land 

 animals are concerned. It is true that forest 

 animals differ in general appearance from 

 those of grasslands, but the differences in 

 body proportions by no means approach the 

 contrast in growth forms between grasses 

 and trees. The general aspect of aquatic 

 animals stands in marked contrast with that 

 of land forms, and various convergences 

 exist among both series that approach what 

 we understand when a vegetational type is 

 mentioned. Thus the fishhke form of 

 whales, seals, walruses, fossil sea reptiles, 

 tadpoles, certain larvae of lower chordates, 

 and of the whole galaxy of fishes stands in 

 distinct contrast wdth typical terrestrial 

 structures. The sessile animals of coral reefs 

 and oyster banks approach the terrestrial 

 vegetational concept even more closely. 



Contrary to first impression, the fact that 

 animal ecology is based primarily on 

 faunistic considerations tends to simplify its 

 study, since the student of animal relations 

 is not so much tempted to pursue the super- 

 ficial types of inspection that make the 

 carwindow approach one of the charms and 

 also one of the pitfalls of plant ecology. 



The apphcation of even a well-formu- 

 lated generahzation to a given situation may 

 require further research. Thus in the control 

 of mosquito-borne diseases of man, the 

 mosquitoes that transmit epidemic yellow 

 fever behave according to rule. A trained 

 executive can sit at his desk in New York, 

 after he has fully learned the principles in- 

 volved, and give directions which, if faith- 

 fully carried out, will lead to the control of 

 the disease. It is not so with the anophehne 

 mosquitoes that carry malarial parasites. 

 Each type of malarial vector is a special 

 case, and, without further knowledge, the 

 general principles may seem inappHcable to 

 the given situation. In the southeastern 

 United States, malaria is transmitted by a 

 marsh-dwelUng mosquito characteristic of 

 sluggish water; in Italy, by a form that lives 

 in the cold running water of the uplands; 

 in Puerto Rico, by a brackish-water mos- 

 quito. Under such varied conditions the 

 needed local detail is of equal value with 

 knowledge of the underlying general prin- 

 ciples. 



An example of the benefits to be derived 

 from an approach to ecology through gen- 

 eral principles is given in the summarizing 

 paragraph of ocean cinrrents by Sverdrup, 

 Johnson, and Fleming (1942, p. 399), who 

 conclude: 



"From this brief summary it is evident that 

 it is virtually impossible to obtain knowledge 

 of the ocean currents on an entirely empirical 

 basis. If this were to be accomplished, it would 

 be necessary to conduct measurements from an- 

 chored vessels at numerous localities for long 

 periods and at many depths." 



A word is in order about "principles." We 

 do not wash, nor are we competent, to en- 

 ter into a philosophical evaluation and 

 definition of "laws," "concepts," and "prin- 

 ciples." Ecology proceeds, as does any 

 empirical science, (1) by the collection of 

 relevant facts; (2) by the arrangement of 

 these facts into ordered series according to 

 their relations and patterns; and (3) by the 

 development of higher-category knowledge 



