i9i8. Irish Societies. 171 



IRISH SOCIETIES. 



DUBLIN MICROSCOPICAL CLUB. 



October 9. — The Club met at Leinster House, the President in the 

 chair. H. A. Lafferty exhibited preparations of myceHum of a parasitic 

 fungus Colletotrichum linicolum in the epidermal cells of the testa of living 

 flax seed. The fungus, which has been described as a new species in the 

 Set. Proc. Roy. Dublin Society, vol. xv. (N. S.), No. 30, Aug., 1918, causes 

 a leaf-spot and stem lesion disease of flax seedlings and hibernates in the 

 form of dormant mycelium in the testa of infected seeds. 



Dr. G. H. Pethybridge exhibited the ascomycetous fungus Keithia 

 thujina Dur. It was discovered in quantity in July, 1918, on the leaves 

 of young trees of Thuja plicata Don in a nursery at the forestry station 

 of the Irish Department of Agriculture at Baunreagh, in the Slieve Bloom 

 mountains, Queen's County, where it was responsible for the death of many 

 hundreds of three-year old trees. It was also found on an older tree in 

 one of the plantations, but in this case the injury done was not so serious. 

 The fungus was kindly identified by Miss E. M. Wakefield of the Kew 

 Herbarium. This species of Keiihia was first observed by J. J. Davis 

 in 1908, in Wisconsin, U.S.A., on Thuja occidentalis, and was described 

 by E. J. Durand in 1913 {Mycologia, v., p. 6). In 1916 J. R. Weir 

 called attention to a serious disease in young plants of T. plicata 

 Don occurring in the lake region of northern Idaho {Phytopathology, 

 vi., p. 360) caused by the same fungus. The present notice is the first 

 record of the appearance of Keithia thujina outside of North America. 



W. F. GuNN showed a mounted preparation of the capillitium and spores 

 of the myxomycete Hemitrichia Vesparium. The species has not previously 

 been recorded from Ireland, but was found by him in September of this 

 year growing on a decaying sawdust heap near the Glen of the Downs. 



November 13. — The Club met at Leinster House, the President 

 in the Chair. 



H. A. Lafferty exhibited microscopic preparations of Pestalozzia 

 funerea (Desm.). The fungus was found growing on the bark of Ciip- 

 vessiis Lawsoniana twigs, but whether as a parasite or saprophyte was 

 not definitely determined. This fungus has hitherto been unrecorded for 

 Ireland. 



Dr. G. H. Pethybridge exhibited specimens and sections illl^strating 

 the phenomenon of heterocarpism, which, as he had recently found, 

 occurs in Helminthia [Picris) echioides, the Bristly Ox-Tongue, and which 

 does not appear to be widely known. Two quite distinct forms of fruits 

 are borne by each head of this plant. About sixty or so are golden-brown 

 in colour with wrinkled skins, while from three to five more or less 

 resemble peeled bananas. Hetcrocarpy in this plant was dealt with by 

 Dclpino in Mem. R. Accad. d. Sci. d. Inst. d. Bologna (5) iv., 1894, p. 31. 



