258 THE SURVIVAL OF THE UNLIKE. [xiV. 



grown in the soil enforces the same lessons. We know 

 that variations in plants are very largely due to diverse 

 conditions which arise after birth. 



All these variations in land and other physical con- 

 ditions are present in varying degrees in wild nature, 

 and we know that the same kind of adaptations to 

 conditions are proceeding everywhere before our eyes. 

 We cannot stroll afield without seeing it. Dandelions 

 in the hollows, on the hillocks, in the roadside gravel, 

 in the garden — they are all different dandelions, and 

 we know that any one would have become the other if 

 it had grown where the other does. 



But aside from the differences arising directly from 

 physical conditions of soil and temperature and mois- 

 ture, and the like, there are differences which are forced 

 upon plants by the struggle for life. We are apt 

 to think that, as plants grow and crowd each other, 

 the weaker ones die outright, because they were en- 

 dowed with — that is, born with — different capabilities 

 of withstanding the scuffle. As a matter of fact, hoAv- 

 ever, the number of individuals in any area may remain 

 the same, or even increase, whilst, at the same time, 

 everyone of them is growing bigger. Early last sum- 

 mer I staked off an area of twenty inches square in a 

 rich and weedy bit of land. When the first observa- 

 tions were made, on the lOtli of July, the little plat 

 had a population of eighty -two plants belonging to ten 

 species. Each plant was ambitious to fill the entire 

 space, and yet it must compete with eighty -one other 

 equally ambitious individuals. Yet, a month later, the 

 number of plants had increased to eighty -six, and late 

 in September, when some of the plants had completed 

 their growth and had died, there was still a population 



