ASPECTS OF KINETIC EVOLUTION 26 1 



TEMPORARY EFFECTS OF NEW CONDITIONS (NEOTOPISM). 



Experiments to test the effects of different environments upon 

 plants are often interfered with by a temporary stimulation of 

 growth, due, apparently, to the fact that the conditions are new, 

 rather than to any essential superiority of the new place. 



Like travelers in foreign countries they may often behave in 

 a manner very different from their habits at home. Organisms, 

 as well as men, though not built by their environments, are 

 often built into them to such a degree that where the accustomed 

 supports and restrictions are taken away the usual courses of 

 action are no longer followed. New and unexpected character- 

 istics assert themselves, not only or chiefly because the new 

 conditions cause the organism to vary, but because they give it 

 an opportunity to do so, or strengthen and bring to expression 

 some tendency or instability of equilibrium. The new 

 characteristics which have a definite connection with the new 

 environment and are in the nature of adjustments to it may be 

 expected to continue, but there is, in addition, a temporary effect, 

 a temporary lack of adjustment, or a stimulation or aberration 

 which sooner or later disappears. 



This phenomenon may be called neotopism, or the new place 

 effect. It is often strikingly shown in plants, and is not lack- 

 ing in animals. The most familiar example of it is, perhaps, 

 that of the tonic medicines. A vast number of substances, 

 utterly unlike among themselves and having utterly diverse 

 specific actions upon the human system when taken in large 

 quantity, may nevertheless produce the same beneficial effect 

 of temporarily increasing the efficiency of the organism, when 

 taken in extremely small doses. 



Neotopism is also to be reckoned as one of the factors con- 

 tributing to the great vigor and rapid distribution of plants and 

 animals immediately following their introduction into a new 

 region. It is true that they may also have the advantage of 

 immunity from diseases or natural enemies to which they were 

 subject at home, but this is by no means a sufficient explanation 

 of the unusual vigor and fecundity which they manifest for a time 

 and which disappears after a series of years. Many plants, 

 like the Russian thistle, which terrified the agricultural regions 



