PLANTS DEFEND THEMSELVES 51 



the little plants, like mosses and bluets, which grow 

 behind rocks and in deep glens, where they are pro- 

 tected from wind and too much sun. 



There are other plants which close their blos- 

 soms at the least sign of rain, opening them again 

 in sunshine. The pimpernel does this with such 

 consistency that it is called the poor-man's weather- 

 glass. 



Cold weather is believed by many people to kill 

 practically all the plants. This, of course, is as un- 

 true as it would be to say that the bear, hibernating 

 in his den until the warm spring sun shall call him 

 forth, has been killed by the cold weather. There 

 are many aquatic plants which, flourishing beauti- 

 fully during the warm months, as autumn ap- 

 proaches gradually dry up and drop to the bottom 

 of the water until the winter is over. Then they 

 send forth tender young shoots and begin a new 

 year of life. Their so-called "death" has been 

 merely hibernation, a prudent attention to the in- 

 tuitive warning which has come to them to guard 

 themselves against the cold. It is but a strong 

 evidence of the active and dominant instinct of self- 

 defence in plant life. 



