728 JOUENAL OF THE ROYAL HORTICULTURAL SOCIETY. 



The above account illustrates the value of strict scientific investiga- 

 tion, which indicates the practical measures to be taken to prevent this 

 particular form of fungus disease. It shows that spraying is of no service ; 

 on the other hand, it shows that if the seedlings can be kept free from 

 the fungus for the first month of their existence, all danger of infection 



Fio. 304. — Oat Smut {Ustilago avence). 



This fungus can only enter the tissues of the Oat plant when the latter is very 

 young. The fungus grows along with the Oat plant without betraying its presence 

 until the grain is formed, when a sooty black mass of spores is produced^ 



is past. This can easily be done by sowing the seed in soil free from 

 fungus spores. It further shows that a plant once infected remains so 

 through life ; hence the gardener removes all such infected Scillas, &c. 



The same fact, that infection has taken place some time before the 

 fungus appears as a disease on the surface of the plant, holds good in 

 every instance. . It is the province of the specialist to determine the 



