ALPINE PLANTS IN NATURE. 25 



lowlands are taller and looser than those from the 

 mountains. Botanists have made experiments with 

 the object of ascertaining whether soil or climate is 

 the more important factor in effecting this change of 

 habit. An experiment made with Hawkweeds by 

 Nageli seemed to show that soil was the principal 

 agent, since plants grown in the lowlands that assumed 

 a taller and looser habit in good soil reverted to their 

 Alpine character when transplanted into dry sand. 

 But more complete and systematic experiments by 

 Bonnier clearly proved that climate had far more 

 influence than soil. He grew separate portions of the 

 same plant in lowland France and in the Alps, and 

 in order to set any doubts with respect to soil at rest, 

 he transferred earth from one locality to the other, so 

 that the plants grew in similar compost. Trials with 

 various species gave the same result : taUer and more 

 slender stems, looser foliage and larger flower-heads 

 on the lowland than on the mountain plants. 



The interesting experiments made by Bonnier showed 

 that the characteristics of Alpine plants are governed 

 by the cHmate, and further tests, made entirely in the 

 mountains, proved that light has the greatest influence, 

 since plants partially shaded showed a tendency to 

 develop lowland forms. 



The theoretical interest of these experiments lies in 

 the fact that every individual plant is shown to have 

 the latent capacity for assuming different forms — a 

 sufficiently impressive and remarkable power — and 

 the practical value in the proof that it is not soil but 

 light which has the greatest influence on the plants. 



