THE PAGE OF NATURE. 



267 



fruits of the earth, cause incalculable damage. Some of 

 the most destructive diseases of the cereal crops are 

 caused by the ravages of microscopic fungi, which attack 

 respectively the flower, the grain, the leaves, the chaff, 

 and the straw. Those who have seen corn-fields in July, 

 when the flower is bursting through the sheath, must 

 have often noticed several greyish-black heads appearing 

 here and there among the verdant stalks. In some fields 

 these are few and far between ; in others they are 

 more numerous, almost every alternate stalk presenting 

 this amorphous appearance. When one of the heads 



thus affected is pulled 

 and examined, every 

 chaffy scale is found 

 to be filled with a 

 firm black matter, 

 like soot agglutinated 

 by moisture. This 

 strange phenomenon is 

 attributed to the state 

 of the air, to the con- 

 dition of the seed, or 

 to the character of the 

 soil ; but there are 

 few comparatively who 

 are aware of its ve- 

 getable origin, who 

 FIG. 35.-UREDO SEGETUM. know that it is owing 



to the development of minute parasitic fungi, favoured of 

 course by unhealthy conditions of the atmosphere and 

 the soil. . To botanists it is known under the name of 



