DUBLIN MICROSCOPICAL CLUB. 423 



TrichopTiyton tonsurans, exhibited.— Tfw Arthur Barker exhibited 

 a sHde of Trichopliyton tonsurans, and drew attention to its myce- 

 lioid growth, occasionally presenting a somewhat torulose appear- 

 ance. 



Microscopical Photographic Negatives, exhibited. — Mr. Wood- 

 worth showed some excellent photographic negatives taken by himself 

 of several microscopic objects — diatoms, insects, various sections, &c. 

 — mounted for employment with the oxyhydrogen lantern ; they 

 were of great sharpness and accuracy of detail. 



Double-spored or Twin'Sporedform of Cylindrocystis Brebissonii ? 

 shown. — Mr. Archer showed the conjugated state of a Cylindro- 

 cystis, which, if taken in the unconjugated condition, would be at once 

 pronounced to be Cylindrocystis Brebissonii, but the zygospore, or 

 rather zygospores, for they were twin, were so remarkably like those 

 o{ Peniiim didymocarpitm, Lundell, as scarcely to differ, except in 

 being notably larger. Thus, these very singular examples suggest 

 oneor other of two conclusions — either that Cylindrocystis Brebissonii 

 conjugates in two ways ; at one time with a single spore, as often met 

 with, and as figured by de Bary (' Untersuchungen ueber die Familie 

 der Conjugaten,' T. VII, fig. 12, 13, 16, 17), and at another time with 

 a double spore or twin spores, like JPenium didymocarpimi, Lundell — 

 or there is a distinct species of Cylindrocystis, so like Oylindrocystis 

 Brebissonii that observation as yet furnishes no tangible distinction 

 in the unconjugated state, but which differs in the conjugated state 

 therefrom. JPenium didy^nocarpvm, Lundell, so like in its conjugated 

 state to the present examples, is a perfectly distinct plant ^er se ; it 

 is very rare in Ireland (found as yet only at Connemara, and once or 

 twice conjugated, quite agreeing with Lundell's figure) ; on the other 

 hand, Cylindrocystis Brebissonii is extremely common, and, indeed, 

 frequently met with conjugated (in the single-spored way). To the 

 former view, for the present, Mr. Archer was inclined to lean, that 

 is, that C. Brebissonii conjugates both ways, but in the double way 

 far more rarely ; indeed, it was the first time he had ever noticed 

 its occurrence. 



2'dth May, 1874. 



Rypertrophied Bark of JJlmus campestris. — Dr. E. Perceval 

 "Wrio-ht exhibited a section of the bark of TTlmus campestris, from 

 Killarney, remarkably hypertrophied, producing on the small 

 underwood stems several irregular, elevated, horizontal ribs of con- 

 siderable height, and forming almost a disconnected or independent 

 growth of extremely exuberant degree of development. 



Nitzschia grandis, Kitton, and Amphora lanceolata, Cleve, ex- 

 hibited.— 'Rev. E. O'Meara presented a slide containing a new species 

 of Nitzschia, mounted by our corresponding member, Mr. Kitton, 

 and named by him N. grandis.— Re also showed Amphora lanceo- 

 lata, Cleve C Diat. fr. Spitzbergen'), and which Mr. O'Meara had 

 found in great abundance in gatherings made at Spitzbergen by 

 Jlev. Mr. Eaton. 



