CHAPTER IV. 



THE AGENCIES CONCERNED IN THE DISTRI- 

 BUTION AND PROPAGATION OF NOXIOUS 

 WEEDS. 



The means or agencies concerned in the 

 distribution and propagation of noxious 

 weeds are chiefly the following: seed grain, 

 grass seed, clover seed, etc. ; farm live 

 stock ; purchased feed stuffs ; farmyard 

 manures ; packing-cases, crates, etc., that 

 have been used for the carriage of goods ; 

 road and farm vehicles, etc. ; implements of 

 tillage ; thrashing machines ; railways ; birds ; 

 wild animals ; waters ; winds ; and the inher- 

 ent powers of the weeds themselves. Some 

 of these means or agencies are entirely 

 under the farmer's control, as the last men- 

 tioned ; some of them are but partially under 

 his control — that is, as far as weed distri- 

 bution is concerned — as the vehicles that 

 pass along his roads or are used upon his 



