LEGISLATION AND DISEASE 219 



The following specific cases may be quoted in support of 

 this statement. 



According to the Prussian Statistics Bureau, the losses 

 in Prussia during the year 1891 from grain rust attacking 

 wheat, oats, and rye, amounted to ^"20,628,147. The 

 Year-Book of the United States Department of Agriculture 

 for 1897 estimates the injury caused by fungi during 

 that year in the United States as amounting to about 

 ^40,000,000. In Australia the loss in the wheat harvest 

 of 1890-91, on account of rust, was estimated at 2, 5 00,000. 

 Data of a similar nature for this country are not forth- 

 coming, but our average annual loss is probably not less 

 than that of other countries, as mildew, rust, etc., are 

 always more or less in evidence. 



Can this serious annual loss be prevented, or reduced in 

 amount, is the question which naturally suggested itself. 



Undoubtedly yes, as proved by results obtained, more 

 especially in the United States, and in some European 

 countries; but, speaking broadly, attempts in this direc- 

 tion have been confined to checking the spread of a given 

 disease, after its appearance, and as such have not touched 

 the root of the matter. The primary cause must be re- 

 moved before any enduring benefit can result. Legislation 

 has also been called in aid, but again, as will be shown, 

 minor details have received much consideration, whereas 

 broad, underlying principles have been overlooked. 



It is a well-known fact that diseases are constantly 

 appearing in new localities, and a point of primary import- 

 ance is to determine with certainty by what means such 

 diseases are conveyed. This subject can be most con- 

 veniently discussed under two distinct headings, as follows. 



i. Diseases that appear when the host-plant is introduced 



