£02 The Irish Naturalist i May, 



DUBLIN MICROSCOPICAL CLUB. 



March ii. — The Club met at Leinster House, Dr. G. H. Pethybridge 

 (Vice-President) in the chair. He exliibited potato tubers affected with 

 the disease known as Black Scab, Wart}- Disease, Potato Rosette, &c., 

 due to a fungus in all probability identical with that described b}' 

 Schilberszky in the Ber. d. dent. bof. Ges. xiv., 1896, as occurring in 

 Hungar}', to which the name Chrysoplydis endohiotica was given. The 

 tubers exhibited had been obtained from England, inasmuch as the 

 disease has so far not been reported in Ireland, and it is to be hoped that 

 it will not appear here. The disease has been known in England for 

 some twenty years, but it is only some eight years or so since scientific 

 investigation was brought to bear on it. In 1899 Dr. W. G. Smith, of 

 Leeds, investigated it, but did not identify the cause ; in 1902 it was re- 

 ported on from Kew, but a mistake was made in identifying the fungus, 

 and the first correct account of the fungus seems to have been given by 

 Professor Potter in that year. The disease, which has become widely 

 spread in Great Britain during recent years, is much more destructive 

 than ordinary potato scab, and exceedingly difficult to eradicate when 

 once established. Sections of the diseased tissues were exhibited under 

 the microscope, which showed the thick-walled, resistant, resting spores 

 of the fungus, each occupying a single cell of the potato tissue. The 

 germination of these spores (or sporangia — for possibly they may be such) 

 has not yet been observed. An illustrated leaflet on this disease has 

 recently been issued by the Department of Agriculture and Technical 

 Instruction for Ireland, and a sharp look-out should be kept by everyone 

 growing potatoes, whether in a large or small way, so that, if it should 

 appear in Ireland, means may be immediately taken to stamp it out. 



R. Southern, B.Sc, exhibited specimens of the rhabdocoele Turbel- 

 larian Alacrorhytuhns croceus, P'abr. Several individuals were obtained 

 from seaweeds in rock-pools at Malahide, in February of this year, when 

 they were quite mature. The specimen exhibited was mounted in a 

 mixture of glycerine and acetic acid, which, though of no value for per- 

 manent preparations, is useful for temporary mounts. The worms 

 contained large egg-capsules, lying in front of the characteristic chitinous 

 penis-sheath. This species has been recorded from Valencia Harbour, 

 by Gamble ; from several localities in Great] Britain ; and from various 

 parts of the North P)uropean shores. 



F. W. Moore, M.R.I. A , exhibited a plant of the curious and rare little 

 orchid Kestrepia xanthothalma, from Guatemala. The small flowers are 

 borne at the back of the leaves and face downwards. He also exhibited 

 the labellum under the microscope, to show the peculiar manner in which 

 the blotches of colour, due to coloured cell sap, were distributed through 

 the tissues. 



J. N. Hai.berT, IVI.R.I.A., exhibited a rare neuropterous insect, Psectra 

 diptera, Burmeister, which he found amongst bushes on the banks of the 

 River Slaney near Wexford, in July. 1900. The insect is chiefly remark- 

 able for the rudimentary condition of the second pair of wings in th^ 



