188 PROCEEDINGS OF SOCIETIES. 



Sulphate of Copper at different Temperatures," and exhibited a 

 series of specimens under the microscope. 



Mr. J. Slade read a paper on " The Microscopic Structure of the 

 Shells of Crustacea," which he illustrated with several coloured 

 diagrams. 



Dr. Braithwaite presented specimens of mosses in continuation of 

 the series, and called attention to four as being rare, viz. Fissidens 

 exilis, found by Mr. W. W. Eeeves ; Hypnum impotens and Bux- 

 haumia aphylla, found by Professor Lavvson ; and Hypnum llle- 

 cebrttm, found by Dr. Braithwaite, who also exhibited specimens of 

 Wolffia arhiza, the smallest of the British flowering plants, and 

 recently discovered here. 



Thirty members were elected. 



Dublin Microscopical Club, 

 16t7i, January, 1868. 



Dr. Moore, alluding to the exhibition at last meeting of the 

 Protonema of ScJnstosteya osmundacea, by Dr. Dickson, brought 

 forward a frond of this little moss, which he had in cultivation, 

 forming a very pretty low-power object. 



Eev. E. O'Meara exhibited a new Navicula, to be hereafter 

 described. 



Eev. T. Gr. Stokes exhibited a fine specimen of Actinopfyctts 

 tricingulus ; also, on the same slide, a test of a Difflugia obtained 

 from guano, which had withstood the action of the acid used in the 

 preparation of the diatoms. This was a balloon-shaped pellucid 

 form, externally marked by reticulations. 



Dr. Collis exhibited sections of a wart, which was passing into 

 cancerous degeneration. The sections showed the first two stages 

 of this degeneration, and corresponded with wonderful accuracy to 

 some diagrams on the subject which had appeared in his work on 

 ' Cancer and Tumours.' In one portion of the section, the cuta- 

 neous papillae were seen in a state of simple hypertrophy, with the 

 epithelial covering lying in a dense horny mass upon the surface 

 of each papilla, and crowded irregularly in the interspaces between 

 the papillae. In a neighbouring part, the horny epidermis had 

 encroached on some of the papillae, and, by its pressure, produced 

 ulcerative absorption of them. Traces even of the third stage, or 

 interstitial deposit of the eperdermic scales in the substance of the 

 skin, could be faintly made out in some points. The difference of 

 colour and of refractive power in the true skin and the epidermis 

 brought out these points with more than usual sharpness. 



20th February, 1868. 



Dr. John Barker mentioned his having seen in "conjugation" 

 that minute rhizopod Trinema acinus, and described the alternate 



