Current Literature. 71 



throughout the world. The hereditary or taxonomic unit is here 

 the hub of the microcosm. Here also the aggregate is considered 

 as an agent or entity which produces many kinds of activities 

 and adjustments to the environment. 



Associational ecology is devoted to the investigation of the 

 development, inter-relations and responses of animals and plants 

 which are grouped or associated in the same habitats and envi- 

 ronments. In this case the associates in a given association and 

 habitat are considered as a unit whose activities and inter-rela- 

 tions and responses are investigated in the same manner as if 

 it were a single animal or plant. The interactions among mem- 

 bers of an association are to be compared to the similar relations 

 existing between the different cells, organs or activities of a 

 single individual. Such groupings have a composition which has 

 developed into an arrangement or "spacing" of individuals within 

 it, and which produces a particular plan or pattern, as a result 

 of the innumerable responsive activities' on the part of individ- 

 uals which live together. For example, when the tiers of vege- 

 tation in a forest are treated as a unit, the entire history of the 

 plants in the habitat is considered as a response to the conditions 

 of life therein. In this form of study the association becomes- 

 the center of all radiating relations and responses. Such an as- 

 sociation is an agent which transforms substance and energy, 

 producing varied physiological conditions and responses in that 

 continuous process of adjustment which constitutes life. 



In discussing the value of ecological surveys, the author con- 

 cludes that their main advantages are : ( i ) the record of natural 

 environments and their associations for future generations; (2) 

 the study of natural biotic conditions, giving a perspective not 

 derived in any other way; (3) the clearer conception of the 

 dynamic relations of the balance of nature, biotic base and climax 

 associations; (4) emphasis of the process and interpretative 

 phase of scientific investigation over that of purely descriptive 

 study; (5) facilitating the invention of multiple working hy- 

 potheses which bear upon animal and plant responses in nature; 

 (6) furnishing important conceptions to the study of the pro- 

 cesses of adaptation and the struggle for existence; (7) furnish- 

 ing important general principles of great value in applied ecology ; 

 (8) furnishing one of the best methods of learning how to get 



