MILDEW AND BRAND. 49 



Look down at tlie green leaves_, especially the lower 

 ones^ and you will soon find one apparently grown 

 rusty. The surface seems to be sprinkled with 

 powdered red ochre^ and grown sickly under the 

 operation. Pluck it carefully^ and examine it with 

 a pocket lens. Already the structure of a healthy 

 leaf is famihar to you^ but in the present instance 

 the cuticle is traversed with numerous longitudinal 

 cracks or fissures^, within which^ and about their 

 margins^ you discern an orange powder^ to which 

 the rusty appearance of the leaf is due. Further 

 examination reveals also portions in which the 

 cuticle is distended into vellowish elono^ated 

 pustules^ not yet ruptured^ and which is an earlier 

 stage of the same disease. This is the ^^ rust ^^ of 

 the agriculturist, the Trichohasis riibigo-vera of 

 botanists, the first phase of the corn mildew. 



To know more of this parasite, we must have 

 recourse to the microscope; having therefore col- 

 lected a few leaves for this purpose, we return 

 homewards to follow up the investigation. We 

 will not stay to detail the processes of manipu- 

 lation, since these will not ofi'er any deviation from 

 the ordinary modes of preparation and examination 

 of delicate vegetable tissues. 



The vegetative system of the ^^rust,^^ and similar 

 fungi, consists of a number of delicate, simple, or 

 branched threads, often intertwining and anasto- 

 mosing, or uniting one to the other by means of 

 lateral branchlets. These threads, termed the 



E 



