THE RELATION OF INSTITUTIONS TO ENVIRONMENT. 



By W J MoGee. 



THE RELATIONS OF ORGANISMS. 2 



The career of the organism, as individual species or larger group, 

 may be considered as the resultant of two forces, viz, (1) the initial or 

 directing force operating through heredity, and (2) the secondary or 

 modifying force operating through interaction with environment. 



The potency of environment in shaping the career of the organism is 

 illustrated by the forest. Primarily the plant depends for existence on 

 soil and climate, and vitality fails if these conditions are adverse; when 

 soil and climate are measurably favorable the fitter plants strive for 

 supremacy and some tower above their competitors. Commonly the 

 trees bear multitudes of seeds, that the species may survive even 

 though many .seeds fall on stony ground and many young shoots may 

 choke among brambles; the cypress, pine, and other trees combine to 

 form dense and lofty mantles of foliage beneath which alien plants are 

 smothered; and through these and other means forests are produced. 

 Initially the tree strives against alien species, but when its kind comes 

 to prevail the trees strive against one another and the strongest, lofti- 

 est, and hardiest survive; and thus internecine strife as well as strife 

 against the alien makes for excellence among trees. So the forest is 

 shaped by environment, beginning with external conditions and ending 

 with the mutual relation between individuals; and the career of the 

 forest tree is one of ceaseless struggle, chiefly against other plants, 

 both akin and alien, through which all its features are molded. 



The potency of environment in shaping organisms is still more 

 clearly shown in desert lands. Here the strife for existence is chiefly 

 between the organism on the one hand and the physical conditions of 

 climate and soil on the other; here the plants strive to perpetuate 

 their kind by individual longevity rather than by multiplication of off- 

 spring, so that with most species seeds are are reduced in number, 

 while with some species fruiting becomes a disease, perhaps fatal; here 



'Saturday lecture iu Assembly Hall of the United States National Museum, May 

 23, 1896. Delivered in the absence of the author by Mr, Frank Hamilton Gushing;. 



2 The first division of the address is a resume of the earlier lectures of the series, 

 especially of the five biologic addresses constituting the first course. 



701 



