186 



ITS EAELT INTRODUCTION. 



character of a perennial, and can be made to last three 

 or four years, or even more, by simply preventing it 

 from running to seed. This plant is seen in Fig. 147, 

 its leaf is shown in Pig. 148, and its fruit magnified in 

 Fig. 149. 



Fig. U9. 



Fig. 147. Bed Clover. 



The introduction of cloyer into England, it is often 

 said, produced an entire revolution in her agriculture ; 

 and, indeed, when we consider how important a part it 

 plays in our own system of farming, we can with diffi- 

 culty imagine how our ancestors ever got on at all in 

 farming without it. Be this as it may, it is certain that 

 it led to many of the most important improvements in 

 the rotation of crops. Clover is very properly regarded 

 as a fertilizer of the soil. The action of its long and 

 powerful tap-roots is not only mechanical, — loosening 

 the soil, and admitting the air, — but also chemical, serv- 



