120 MICROSCOPIC FITNGI. 



stroll in the grounds, and when the well-known 

 leaves of the coltsfoot are descried, the under sur- 

 face of the first leaf will doubtless give proof of the 

 presence of the fungus in question, by the orange 

 spores amongst its dense woolly hairs. Sometimes 

 the leaf is almost covered beneath with the bright 

 orange-coloured dust. This is the coltsfoot rust 

 (ColeosporiumtussilaginiSf Lev., plate VIII. fig. 1 80), 

 which may serve as a type of the rest. It may be 

 observed that a species of cluster-cup, or JEcidium, 

 with spores of nearly the same colour, is also to be 

 found on the leaves of the same plant ; but in this 

 case the upper surface of the leaf has also corre- 

 sponding purplish spots, and, what is of still more 

 importance, the spores are seated in small fringed 

 cups. The rust is common till the wintry frosts have 

 set in, and is far more conspicuous than the cluster- 

 cups. A kind of di-morphism prevails in all the 

 species of this genus. Some of the pustules resolve 

 themselves into a kind of powder, whilst others 

 remain entire and solid. Generally there is the 

 largest proportion of globose, dust-like, free spores, 

 produced in the earliest developed fungi, whilst they 

 become more rare towards the close of the season. 

 The permanent spore-spots consist of obovate 

 cellules placed side by side, each of which is divided 

 transversely by three or four septa, and is filled with 

 an orange-red endochrome (plate VIII. fig. 181); 

 the exterior being enveloped in a kind of mucous 

 layer. The arrangement of spores when packed 



