320 PKOCEKDINGS OF SOCIETIES. 



lated in abstract Q. J. M. S., 1873, pp. 156—163), exhibited 

 examples of Micrococcus (Monas) prodigiosus (Ehr.), Cohn, which 

 had occurred on some slices of raw (" diseased ") potatoes which 

 had been left lying under a bell-glass. He remarked on the 

 points dwelt on by Cohn as regards the Sphcerohacteria (Cohn), 

 to which sub-group the curious production now shown belong, 

 falling under the category of " Pigment Bacteria," on account of 

 the remarkable colours evinced, not by the cells themselves, but 

 apparently due to the matrix. These examples showed at first a 

 blood-red colour, but more recently a deep brick-red, changing to 

 a brown. Prof. Cohn's illustration (Q. J. M. S., PI. V, fig. 1) 

 gives the cells as if typically globular, in the present instance 

 they were elliptic, say one third longer than broad (the longest 

 scarcely ^-^'oo") ! ^^^ walls very delicate. These cells are de- 

 scribed as colourless, but they appeared rather to evince that bluish 

 hue characteristic of phycochrome, and in tint came very near 

 some i\ro*^oc-cells. It might be worthy of remark that, though 

 the production flourished best on the potato-surface, a very good 

 crop had become developed underneath the slice, covering the 

 lower surface of a piece oi paper on which the potato-slice lay ; 

 thus too nearly, if not quite, in the dark — that is to say, the 

 paper (to some extent, however, macerated) was between the 

 potato and the Micrococcus-stratum. 



19th March, 1874. 



Fern-scales,and a new Fish-trough, exhibited. — Mr. Porte showed 

 a series of mounted preparations of fern-scales from various ferns, 

 some, when polarised, were of singular beauty.— He also showed a 

 new trough of his own design and construction for viewing the cir- 

 culation of the blood in the tail of a minnow. This consisted of a 

 glass plate about three inches square, having two narrow wedge- 

 shaped pieces of tin, about a quarter of an inch thick, and taper- 

 ing to a point, cemented to the plate near its middle and about 

 half an inch apart ; over these a slip of glass was cemented, thus 

 enclosing a narrow wedge-shaped space, " tapering to nothing " 

 below, and sealed all round except at the upper oblong opening 

 into which the fish is dropped tail foremost. 



Pinnularia cardinalis, very rare in Ireland, exhibited. — Kev. E. 

 O'Meara showed a specimen of Pinnularia cardinalis from a pond 

 near Armagh. This is of extremely rare occurrence in Ireland. 

 Smith attributes it to the Lough Mourne deposit, but though he 

 (Mr. O'Meara) had often searched for it there, he had never been 

 fortunate enough to find it. In a peat deposit from Dromore, 

 Co. Down, kindly supplied by Mr. Gray, of Belfast, the middle of 

 a valve was discovered, but no perfect example had previously 

 come under his observation. — Mr. O'Meara also showed examples 

 of Bhahdonema Torellii, Cleve, " Diatoms of the Arctic Sea." The 

 form occurred not unfrequently in some gatherings made at 

 Spitzbergen by Eev. A. E. Eaton. 



