THE CAUSES OF THE STRUGGLE, 299 



shapes and sizes of leaves, although fairly uniform, 

 yet a careful observer will notice minute differences 

 in every one, and the same thing is more patent in 

 flowers. 



It is hardly necessary to say anything more to 

 prove that individuality does exist among plants, 

 as every gardener will be able to verify the fact 

 from his personal experience. The great questions 

 are, why does every one differ from the others, 

 and how does this come about? This factor in 

 evolution is not something belonging to a bygone 

 time, but a real force continually at work. As 

 individuals are born every day we ought to have 

 no very great difficulty in discovering the why and 

 how of these differences. Nevertheless, like other 

 life problems, the causes of variation are still 

 almost unknown, and it is doubtful whether we 

 shall ever be able to obtain anything like certainty 

 as to their origin. 



However, even tentative theories are useful to 

 the naturalist, and perhaps the views of an ob- 

 server in the tropics may be considered interesting, 

 even if they are not acceptable. We do not claim 

 originality, in fact, our opinions are the result of 

 study and research, modified probably by our 

 own individuality. We have found them useful 

 in many ways, and especially as means of ar- 



