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. 
