ECOLOGY AND BIOLOGY 315 



these differently located areas. This correspondence is probably much 

 more striking physiologically than in the matters of interrelation of 

 species because in some formations certain groups, as, for example, 

 antelopes in African steppes, are especially numerous, while in a 

 corresponding situation in South America they are very few. 



As has already been suggested, correspondence is not limited to 

 the gross characters of extensive formations, but is -equally true of 

 the more local communities. In matters of correspondence of species 

 there are often striking correspondences within the groups of formation 

 indicated above. For example, there is a striking correspondence in 

 behavior between the meerkats of the steppes of East Africa (3) and 

 the prairie dogs of our own steppe, both being grasslands but differ- 

 ing in climate. Considering a local formation, as that of the sandy 

 beaches of the sea and very large lakes, we note that along the New 

 England coast and around the shores of Lake Michigan the moist, 

 sandy beaches are inhabited by the larvae of the beach tiger-beetle 

 (Cicindela hirticollis) (Fig. 134, p. 179). Along the Gulf Coast at Galves- 

 ton, Texas, we find the larvae of C. saulcyi inhabiting almost identical 

 situations, holes of about the same depth, etc., while Dr. Horn (203) 

 describes a different larva in like situations and with like habits on the 

 coast of India. 



Still, with all that has been said, matters of agreement of different 

 animal communities in different parts of the world are largely theoretical, 

 and while apparently logically well grounded, the general statement 

 must be treated with due caution and subjected to experimental test 

 as soon as possible. Such testing will involve careful experimental 

 study of the communities of two like environments under rigidly con- 

 trolled and carefully measured conditions. 



VI. RELATIONS OF ECOLOGY TO OTHER BIOLOGICAL SUBJECTS 



The environmental processes which we are discussing are those in 

 which organisms have existed since their origin on earth. The stresses 

 and strains to which organisms have been subjected have been in the 

 same direction for long periods. Now that we have learned much 

 concerning organic response to environment, such as physiological 

 response, behavior response, and structural response, we note at once 

 that processes of adjustment and equilibration of living substance may 

 bear important relations, on the one hand to environmental processes, 

 and on the other to the physiological aspect of biological phenomena. 



