22 BOARD OF AGRICULTURE. [Pub. Doc. 



for existence, then, is inevitable, and it must be severe. It 

 follows as a necessity that those seeds grow or those plants 

 live which are best fitted to grow and live, or which are 

 fortunate enough to find a congenial foothold. It would 

 appear at first that much depends upon the accident of falling 

 into a congenial place, or one unoccupied by other plants or 

 animals ; but, inasmuch as scores of plants are contending for 

 every unoccupied place, it follows that everywhere only the 

 fittest can germinate or grow. In the great majority of cases, 

 plants grow in a certain place because they are better fitted 

 to grow there, to hold their own, than any other plants are ; 

 and the instances are rare in which a plant is so fortunate as 

 to find an unoccupied place. We are apt to think that plants 

 chance to grow where we find them, but the chance is deter- 

 mined by law, and therefore is not chance. 



Much of the capability of a plant to persist under all 

 this struggle depends, therefore, upon how much it varies ; 

 for the more it varies the more likely it is to find places of 

 least struggle. It grows under various conditions, — in sun 

 and shade, in sand and clay, by the sea-shore or upon the 

 hills, in the humidity of the forest or the aridity of the 

 plains. In some directions it very likely finds less struggle 

 than in others, and in these directions it expands itself, mul- 

 tiplies, and gradually dies out in other directions. So it 

 happens that it tends to take on new forms or to undergo an 

 evolution. In the mean time, all the intermediate forms, 

 which are at best only indifferently adapted to their condi- 

 tions, tend to disappear. In other words, gaps appear 

 which we call "missing links." The weak links break and 

 fall away, and what was once a chain becomes a series of 

 rings. So the "missing links" are among the best proofs of 

 evolution. 



The question now arises as to the cause of these numer- 

 ous variations in animals and plants. Why are no two indi- 

 viduals in nature exactly alike? The question is exceed- 

 ingly difficult to answer. It was once said that plants vary 

 because it is their nature to vary ; that variation is a neces- 

 sary function, as much as growth or fructification. This 

 really removes the question beyond the reach of philosophy ; 

 and direct observation leads us to think that some varia- 



