INFLUENCE OF ENVIRONMENT 109 



A very dry spring causes the grasses of a meadow to grow very 

 little, and remain lean and puny ; so that they flower and fruit after 

 accomplishing very little growth. 



A spring intermingled with warm and rainy days causes a strong 

 growth in this same grass, and the crop is then excellent. 



But if anything causes a continuance of the unfavourable environ- 

 ment, a corresponding variation takes place in the plants : first in 

 their general appearance and condition, and then in some of their 

 special characters. 



Suppose, for instance, that a seed of one of the meadow grasses in 

 question is transported to an elevated place on a dry, barren and stony 

 plot much exposed to the winds, and is there left to germinate ; if 

 the plant can live in such a place, it will always be badly nourished, 

 and if the individuals reproduced from it continue to exist in this 

 bad environment, there will result a race fundamentally different from 

 that which lives in the meadows and from which it originated. The 

 individuals of this new race will have small and meagre parts ; some 

 of their organs will have developed more than others, and will then be 

 of unusual proportions. 



Those who have observed much and studied large collections, have 

 acquired the conviction that according as changes occur in environ- 

 ment, situation, climate, food, habits of life, etc. , corresponding changes 

 in the animals likewise occur in size, shape, proportions of the parts, 

 colour, consistency, swiftness and skill. 



What nature does in the course of long periods we do every day 

 when we suddenly change the environment in which some species of 

 living plant is situated. 



Every botanist knows that plants which are transported from their 

 native places to gardens for purposes of cultivation, gradually undergo 

 ■changes which ultimately make them unrecognisable. Many plants, 

 by nature hairy, become glabrous or nearly so ; a number of those 

 which used to lie and creep on the ground, become erect ; others 

 lose their thorns or excrescences ; others again whose stem was 

 perennial and woody in their native hot chmates, become herbaceous 

 in our own climates and some of them become annuals ; lastly, the 

 size of their parts itself undergoes very considerable changes. These 

 effects of alterations of environment are so widely recognised, that 

 botanists do not like to describe garden plants unless they have been 

 recently brought into cultivation. 



Is it not the case that cultivated wheat (Triticum sativum) is a plant 

 which man has brought to the state in which we now see it ? I should 

 like to know in what country such a plant lives in nature, otherwise 

 than as the result of cultivation. 



