138 ELEMENTARY BOTANY 
Too high a temperature, as we have seen in the experiment of 
boiling seeds, kills and renders growth impossible. 
All these experiments show that a plant is affected by 
external conditions, such as light, temperature, moisture ; 
thus it can adapt itself to varying conditions. A land plant, 
for instance, does thrive if grown in water, its roots being 
able to adapt themselves to the different medium. . This 
power of adaptability is characteristic of all living things. 
