114 MICEOSCOPIC ruxGi. 



obtrusive of the dust-like fungi. It is not confined 

 to roses ; but the meadow- sweety on which it is 

 also found, does not grow in localities where its 

 parasite is so liable to meet the gaze of the ordinary- 

 wayfarer. The habit of this rust is more or less 

 that of those which are associated with it. The 

 pustules are not small and orbicular as in most 

 instances in other groups (except Polycystis), but 

 are large and irregular_, and generally but few 

 together or single. The spores are variously co- 

 loured_, and have peduncles, or footstalks, of a 

 greater or less length. In the rose rust these 

 spores are profuse, but the peduncle is short (plate 

 YII. fig. 148). 



Plants of the pea and bean tribe are Hable to 

 be attacked by one of these rusts, and in this in- 

 stance the spores are so characteristic that no one 

 could well confound them with any other. Exter- 

 nally it appears as an irregular brownish pustule, 

 breaking through the epidermis and filled with an 

 impalpable powder, not unlike a pinch of ^' brown 

 rappee '' snufi". The spores are ovoid, with a very- 

 long peduncle, whence its name {Uromyces appencli- 

 culata). It appears on a great variety of plants, but 

 from the peculiarity of the spores (plate YII. fig. 

 150), is easily recognized. Our figure represents 

 it on the leaf of a vetch (plate YII. fig. 149). 

 Almost at the commencement of this volume 

 (Chap. III.) we had occasion to refer in detail to 

 some experiments made by De Bary on the spores 



