180 TILLEES OF THE GEOUND CHAP. 



parasite is introduced by chance from America ; it 

 attacks the carefully kept vineyards, and whole 

 communities are half ruined. 



These are only two cases out of many, two out- 

 standing cases ; but all through his history as a 

 cultivator man has had to keep up this ceaseless 

 struggle. It is a struggle in which he cannot stop 

 to rest for an instant, a heroic struggle which has 

 made many heroes. It is the green plants only 

 which can bring from the sun's rays the energy 

 necessary for life, and therefore man must grow green 

 plants, or die. It is the starch and sugar which 

 the green plants make which enable us to use our 

 muscles. It is the green plants which form the 

 coal which moves our machines. 



In the long-run, it is the green plant which moves 

 the whole world of living things, and therefore the 

 battle of the green plant is our battle. The potato 

 disease, the vine disease, the wheat blight are so 

 many threats against our supremacy ; we must 

 conquer them or perish. 



We have read how Adam in the Garden of 

 Eden was given dominion over the beasts of the 

 earth, " over the fish of the sea, and over the fowl 

 of the air, and over the cattle, and over all the 

 earth, and over every creeping thing that creepeth 

 upon the earth " ; but over the enemies of his 

 cultivated plants he was not given dominion, that 



