44 The Irish Naturalist. [February, 



PROCEEDINGS OF IRISH SOCIETIES. 



Royal Zoological Society. 



Recent gifts include a number of Rudd from Mr. F. Godden, a Great 

 Northern Diver from Mr. R. Warren, a Pheasant from Dr. A, Traill, and 

 a Royal Python from Captain J. R. D. Robertson. Two Seals have been 

 acquired by purchase. 



4,447 persons visited the Gardens during December. 



Dublin Microscopical Club. 



December 15. — The Club met at Leinster House. 



Mr. H.H. DlXON showed intracellular rhizoids of Marchantia polymorpha. 

 Transverse sections of the thallus of this liverwort show intracellular 

 rhizoids similar to those found by the exhibitor in Lumilaria cruciata. These 

 are formed by the ingrowth of the cells surrounding the base of the original 

 rhizoids into the lumen of the latter. The ingrowing cells take on the 

 form of rhizoids and are long and tubular. They may begin their de- 

 velopment while the original rhizoids still possess protoplasmic contents. 

 As many as four intracellular rhizoids have been found contained in one 

 original rhizoid. When the latter is furnished with tuberculate thicken- 

 ngs on the cell wall the ingrowing intracellular rhizoid accommodates 

 itself to the sinuous lumen and assumes a peculiarly irregular contour. 



Mr. Dixon also showed preparations exhibiting the tetrad develop- 

 ment of iecidiospores. Sections passing through the aecidium of ruccinia 

 poamm and stained with Delafield's haematoxylin exhibit, on the lower 

 side of each aecidiospore and in contact with it, a small lenticular cell 

 containing two nuclei. This cell apparently corresponds with the " in- 

 termediate" cellin Chrysomyxa rhododtndri described by De Bary. Often 

 in Puccinia it is divided into two wedge-shaped cells, each with one 

 nucleus. The mother-cell of the aecidiospore is formed by the cutting 

 off of the terminal portion of the supporting hypha. It contains two 

 nuclei lying side by side. These nuclei soon divide and give rise to four 

 nuclei in the cell. The poles of this division usually lie in an oblique 

 plane in the cell. The two lower nuclei are cut off in a small lenticular 

 portion of the cell, and often another cell-division occurs which then con- 

 fines each of these latter nuclei in a single minute cell. These nuclei as 

 the cells are shoved up in the spore-filament soon lose their staining 

 properties, and the cells containing them, and they themselves disappear. 

 The two upper nuclei are enclosed in the spore. They increase rapidly 

 in size. Somewhat above the level in the spore-filament of disappear- 

 ance of the two smaller nuclei, the spore-nuclei unite. 



This tetrad development of the aecidiospores, connected as it probably 

 is with a reduction in the number of chromosomes of the nuclei, and the 

 subsequent fusion of the spore-nuclei, seems to be of great interest, 



Mr. M'Ardle exhibited Blasia pusilla, L,., which was collected last 

 November in the Mourne Mountains, Co. Down, by the Rev. H. W. 

 J^ett, M.A. The specimens shown bore young fruit, and the curious flask- 



