Marts Work on the Farm 359 



exhaust the list ; and even the watercress, which is 

 humble enough at home, has become so wildly luxuriant 

 in some parts as actually to dry up sluggish streams 

 and cause much inconvenience to the sheep. 



Some of the accidental colonists, on the other hand, 

 have turned out real blessings such, for instance, as a 

 coarse species of grass which somehow found its way 

 to Australia from India, as is supposed. In Arabia, as 

 well as in India, this grass supplies food for cattle in 

 districts which would otherwise be desert and unin- 

 habitable ; and it is of incalculable service in the 

 warmer parts of Australia, flourishing where other 

 fodder-plants cannot stand the heat, and keeping 

 luxuriantly green the district round Sydney, which 

 before its coming had been withered and desert-like 

 throughout the summer and autumn. 



Such, then, are some of the more striking changes 

 which man has made, intentionally and unintentionally, 

 in the appearance of the green world. They began as 

 soon as he began to cultivate the soil and interfere 

 with the natural labourers, and they have been going 

 on ever since more and more rapidly, especially during 

 the last three hundred years. And what we see now 

 taking place in America and Australia may serve to 

 remind us of what has been done in Europe ; for here, 

 too, the space now occupied by fields, orchards, gardens, 

 as well as by towns and villages, was covered in bygone 

 times by a dense growth of forest and underwood and 

 green things, of nature's planting. 



And so, also, with the crops. If those grown in 

 Australia are all foreigners, so, too, are most of those 

 grown in Europe ; for, though in many cases we have 



