444 



THE AMERICAN NATURALIST [Vol. XL VIII 



tribution. Upon investigation, it begins to appear that 

 plant and animal assemblages are coextensive parts of a 

 biotic association, composed of both plants and animals, 

 and this association as a whole constitutes the real ter- 

 restrial community of living organisms. Plant and ani- 

 mal assemblages are mutually interdependent ; the plant 

 assemblage dominates in established associations. Plant 

 and animal assemblages correspond in geographic dis- 

 tribution, in distribution into communities, and in more 

 detailed distribution within the habitat. They are made 

 up of ecologically similar groups correlated with the 

 same physical conditions or with each other. Though 

 there are few direct relations between particular species 

 of plants and animals, it so happens that within any 

 restricted region, particular collections of animal species 

 come into regular association with particular collections 

 of plant species, the species composition within the habi- 

 tat exhibiting a greater or less degree of uniformity, 

 except for minor irregular or derived elements. The 

 more restricted in area, or uniform in biological condi- 

 tions, this region is, the greater uniformity of the collec- 

 tion of species. Climatic and extensive associations show 

 a higher degree of uniformity than local or primitive 

 associations. 



VII. REFERENCES 

 Special References 



(A) Shelford, V. E. 



1911b. Physiological Animal Geography. Jour. Morph., 22: 551- 

 618. 



(B ) . 



1912a. Ecological Succession. IV. Vegetation and the Control 

 of Land Animal Communities. Biol. Bull, 23: 59-99. 



(C) — - . ^ c t - ' T t \ G o r Soc 



of Chicago, Bull. No. 5, p. 362. Chicago. 



(D) Vestal, A. G. 



1913fl. Lo,-;,] Distribution of Gr:i^h..ppors in delation to Plant 



(E) . 



1913b. An Associational Study of Illinois Sand Prairie. Bull. 



III. State Lab. Nat. Hist., 10: 1-96. 



Adams, C. C. 



1913. Guide to the Study of Animal Ecology, p. 183. New York. 



