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33. — On Miceoscopic Ftjkgi. 



By E. M. C HATER. 

 [Read 10th May, 1877.] 



The subject of my paper, Microscopic Fungi, is one of such 

 wide extent that it is only to a section of it that I propose to ask 

 your attention this evening, viz. to those minute fungi which are 

 found on living plants, and of these I shall select those that are 

 most likely to be met with and are easily discovered. Should any 

 of our members wish to make a study of these really interesting 

 bodies, I would advise them (if they have not already done so) to 

 procure Mr. Cooke's book on the subject, to which I am chiefly 

 indebted for the information my sketch contains. 



One of the earliest of our spring flowers, and one of the best 

 known, is the lesser celandine or pilewort, Rammculus Ficaria. If 

 you examine a cluster of leaves of this plant, especially if it is 

 growing in a low and damp locality, you are almost sure to find on 

 the under surface of some of the leaves, as well as on the petioles, 

 patches of a yellow colour, and at these spots the leaf or leaf-stalk 

 is more or less thickened. On placing one of these yellow patches 

 beneath a microscope, it is found to consist of a cluster of beautiful 

 little cups having teeth at their margin, and containing a quantity 

 of orange-coloured spores. This fungus is called JEcidimn rammcu- 

 lacearum. The genus JEcidium is included in the family of the 

 Coniomycetes or dust fungi, so called because the spores are the 

 principal feature. This fungus is also to be found in considei'able 

 abundance on the leaves of Ranunculus repens, the creeping crow- 

 foot, and its presence is indicated by spaces of a paler green on the 

 upper portion of the leaves. The stinging nettle, Urtica (lioica, 

 furnishes a home for another member of this genus, JEcidium 

 Urticcc, and although it is scarcely to be found in such quantity as 

 the preceding species, yet it is by no means uncommon. Its 

 presence in the nettle gives rise to some very curious swellings and 

 distortions of the leaves and petioles, so that it is often to be ob- 

 served without difficulty on a cluster of these by no means favourite 

 plants. The shape of the cups and the colour of the spores are 

 very similar to those of the fij'st-named fungus. The sweet and 

 the dog violet have each of them their " cluster-cups." The 

 latter are to be found in quantity in Oxhey "Wood, and doubtless 

 in many other places in the neighbourhood. The buckthorn, 

 Rhammcs catharticus, furnishes us with a species in which the cups 

 are longer than in those of which I have spoken. This is by no 

 means uncommon, and almost eveiy buckthorn bush will be found 

 to have a few leaves bearing this fungus, which is called ^cidiuni 

 crassum. Later in the year a cluster-cup is to be found on the 

 under surface of the coltsfoot, its presence being indicated by a 

 purple spot on the upper surface, and it is generally accompanied 

 by groups of the orange-coloured spores of the coltsfoot rust, but 



