CEREAI. FUNGI. 29 



The cereal fungi have their mycelium present 

 in healthy plants, and under favourable circum- 

 stances they are developed. These are the 

 kinds to which attention will be principally di- 

 rected in the pages of this little book, and they 

 are extremely minute, requiring high powers of 

 the microscope, as well as practised observa- 

 tion, to obtain accurate knowledge of their 

 forms and habits. They generally appear in sori, 

 or patches, consisting of multitudes of spores, 

 that form frequently so many cases inclosing 

 the reproductive sporules, which, as has been 

 stated, float in the atmosphere around us until 

 they light on some place adapted to their 

 growth. Their extreme minuteness allows of 

 their being introduced, by methods hereafter to 

 be explained, into the substance of the tissues 

 of plants, or beneath the epidermis. As they 

 grow on the leaves, or straw, of corn-plants, they 

 raise the epidermis into curious puffy blisters, 

 which they subsequently rupture, in the same 

 way as the large toad-stools have been known 

 to hft up the flag-stones of a paved street in a 

 town in the process of their development. These 

 patches are of different colours, but 'most com- 

 monly either deep yellow, brown, or black. The 

 several parts of the wheat-plant are attacked 



