MILDEW OF WHEAT. 33 



healthy condition. It is a A^ery minute species 

 of sj^hoeria, and may frequently be noticed if the 

 joints are carefully examined. But in the case 

 of the fungus now to be described, the fields, 

 especially of late varieties in certain localities, 

 may be often perceived to be quite blackened 

 by its encroachments, while the grain, as well 

 as the straw, becomes exceedingly deteriorated. 

 On gathering a stem, it will be found com- 

 pletely disfigured by numerous dark blotches 

 of the sori, or patches, often running its entire 

 length. The common name of this disease is 

 mildew, and it has been designated by botanists 

 puccinia graminis, a term supposed to be 

 derived from the Greek word irvKa, (puka,) 

 signifying closely or thickly, and to have refer- 

 ence to the crowded condition in which the 

 little fungi are packed in the several patches in 

 which they grow. When the disease first 

 shows itself, the stem exhibits a number of 

 dark-coloured spots beneath the epidermis, 

 some of which have an orange-coloured tinge, 

 others a deep brown. In a short time, the 

 outer cuticle splits, and dark musty clusters of 

 spores appear in the openings. On examining 

 these with the microscope, they manifest dis- 

 tinct and curious forms. They are seen to be 



B 



