1899] THE CEREAL RUST PROBLEM 345 



in the soil previous to such inoculation, as explained above, then 

 Eriksson's difficulty in accepting the presence of such mycelium as the 

 cause of the disease, on account of its absence from the embryo, both 

 before and immediately after germination, is removed. 



" Ce fut en vain que je cherchai a constater, par le microscope, 

 la presence de germes infectieux internes. Certainement je decouvris 

 dans les tissus peripheriques des graines du froment ridees et 

 deformees par la rouille, un mycelium tres developpe, et meme parfois 

 des especes de nids des spores d'hiver (tehutosporae). Mais toutes les 

 tentatives faites pour trouver un mycelium dans le germe lui-meme, 

 que ce fut dans le germe renferme encore dans la graine, ou dans le 

 germe sortant de la graine a la germination, resterent infructueuses." 



Many people have become so thoroughly accustomed to the annual 

 loss of a certain amount of capital through " rust," " bunt," and " smut " 

 of cereals, that it is looked upon as a matter of course ; or, in other 

 words, such loss is not realised at all ; and it is only during seasons 

 when these diseases are rampant that their presence is forced upon the 

 cultivator, and even then only the amount of loss above the usual 

 annual average is realised. The following figures, taken from official 

 sources, illustrating the amount of loss sustained during an ordinary 

 season, should be sufficient to explain why some governments have 

 considered it incumbent upon them to aid in the endeavour to prevent 

 such enormous losses. 



" Oat smut ( Ustilago avenae) alone destroys each year in the United 

 States over $18,000,000 worth of grain. The other grains, especially 

 wheat, rye, and barley, also suffer severely from smut diseases ; the 

 amount, however, has not been overestimated" (13). 



In the same country we learn that " The aggregate loss from 

 'rusts' (Puccinia sp.) is estimated to be over $-40,000,000 annually" 

 (14). 



The Prussian Statistics-Bureau states that the loss caused by 

 " rust " alone on wheat, rye, and oats, in Prussia, during the season of 

 1891, amounted to a little over £20,000,000 (15.) 



In Australia the loss in the wheat harvest of 1890-91, due to 

 "rust," has been estimated at £2,500,000. 



Finally we learn that in the United States, " Probably it would not 

 be overstating the loss from plant diseases, as a whole in this country, 

 to place it at $150,000,000 to $200,000,000 annually" (16). 



The amount of annual loss in Great Britain arising from plant and 

 animal pests is not officially estimated, but it may safely be assumed 

 that, if half the amount of loss could be prevented, farming and horti- 

 culture would prove to be remunerative occupations. 



An equally formidable array of figures could be quoted from 

 official publications showing the actual gain derived by following the 

 directions issued from experiment stations. 



The question that naturally suggests itself at this point is the 



