SECT. II. DISEASES. 



persed over the surface of the leaf, exactly like that 

 of the seeds of Dorsiferous Ferns bursting their indu- 

 slum. Upon morq minute inspection these patches 

 were found to consist of thousands of small globules 

 collected into groups beneath the epidermis, which 

 they raised up in a sort of blister and at last burst. 

 Some of the globules seemed as if imbedded even 

 in the longitudinal vessels of the blade. They were 

 of a yellowish or rusty brown, and somewhat trans- 

 parent. But these groups of globules have been 

 ascertained by Sir J. Banks to be patches of a 

 minute Fungus, the seeds of which, as they float in 

 the air, enter the pores of the epidermis of the leaf, 

 particularly if the plant is sickly ; or they exist in 

 the manure or soil, and enter by the pores of the 

 root.* This Fungus has been figured by Mr. 

 Sowerby and by Mr. F. Bauer and Grew. It is 

 known among farmers by the name of Red Rust, 

 and as it affects the stalk and leaves only it does not 

 materially injure the crop. 



But there is another species of Fungus, known 

 to the farmer by the name of Red Gum, which at- 

 tacks the ear only, and is extremely prejudicial. In 

 the aggregate it consists of groups of minute globules 

 interspersed with transparent fibres. The globules are 

 filled with a fine powder which explodes when they 

 are put into water. It is very generally accom- 

 panied with a maggot of a yellow colour, that preys 



* Sir J. Banks on Blight, 1805. 





