924 MINNESOTA BOTANICAL STUDIES. 



Motility or non- motility of organisms has little or no direct 

 influence upon the more remote relationships. From the fact 

 that these latter phenomena are most conveniently limited, 

 geographically, it becomes evident that they are largely de- 

 pendent upon the influence of the soil, the climate, moisture, 

 etc. (meteorological influences ) 



The largest and, at the same time, the most remote associa- 

 tion of organisms is the hemispherical. The f aunal and floral 

 differences between the eastern and western hemispheres are 

 considerable, as every naturalist can testify. That the associa- 

 tion is remote is evident from the numerous exotic plants and 

 animals which have become perfectly habilitated. In each 

 hemisphere we again recognize subdivisions of associations, 

 which may be designated as zonal. Here the interdependence 

 is more marked, and is primarily dependent upon the influence 

 of temperature and light. The fauna and flosa of the tropics 

 are essentially different from those of the temperate zone, and 

 this again is different from the arctic. Each of the zonal areas 

 is again subdivided into numerous larger or smaller geograph- 

 ically limited societies, dependent upon local influences, as soil, 

 elevation, moisture, etc. For example, life in the Mississippi 

 valley is essentially different from that in the Rocky mountain 

 system. In each area the organisms are specially adapted to 

 each other and their environment. In each of these divisions 

 we find numerous smaller societies. The process of subdivid- 

 ing could be carried on indefinitely. These smaller subdivis- 

 ions may be natural or artificial, as pond, brooklet, meadow, 

 field, roadside, town, city, etc., each of which has its peculiar 

 fauna and flora. 



Within each of these numerous associations, great and small, 

 we find the organisms acting and reacting upon each other. 

 Here there seems to be a mutualistic association of two or more 

 organisms, while the next door neighbors may be engaged in a 

 struggle with each other for existence. A single example will 

 suffice to illustrate this. The wood peckers and trees evidently 

 form a mutualistic association, while insects and larvae are 

 diligently hunted by the wood- pecker. Weasel and wood- 

 pecker again are antagonistically related. It is not the pur- 

 pose of this paper to enter into the details of biological asso- 

 ciations and societies. It is hoped that these preliminary 

 suggestions will indicate the close relationship existing be- 



