CLUSTEE-CTJPS. 13 



in size from less than one-twelfth of an inch to half 

 an inch in diameter. It is fonnd on several species 

 of Ranunculus, as R. acris, bulbosus, and repens, but 

 most commonly on -B. ficaria. The leaf is thickened 

 at the spot occupied by the parasite, and generally 

 without indication on the opposite surface. Some- 

 times one spot, at others several, occur on the^ 

 same leaf. The peridia are densely crowded to- 

 gether, often arranged in a circinate manner, i.e., 

 like a watch-spring, or the young frond of a fern. 

 The spores are orange, but sUghtly varying in tint 

 on different species of Ranunculus (plate II. figs. 

 12 — 14). One of the smaller clusters, when col- 

 lected before the spores are dispersed, or the teeth 

 of the peridium discoloured, mounted dry as an 

 opaque object, makes a very excellent slide for an 

 inch or half-inch objective ; and the same may be 

 said of many others of the same genus. 



Less common than the foregoing is the species 

 of Mcidiwrn which attacks the violet. The sweetest 

 of flowers as well as the earliest, ia despite both of 

 its odour and its humility, becomes a victim to one 

 or more of the ubiquitous race of fungi. Thickened 

 spots at first appear on the leaves ; the petioles, or 

 flower stem, or even the calyx, become swollen 

 and distorted ; and at length the cluster-cup breaks 

 through. The spots on the leaves upon which the 

 peridia are scattered are yellowish, generally larger 

 than the clusters on the pile-wort, and seldom with 

 more than one spot on each leaf. The peridia, or 



