DUBLIN MICROSCOPICAL CLUB. 107 



swellings are not noticed by Brefeld in his memoir on Penicillium 

 and are therefore of interest. Sometimes they occurred singly, 

 but in general there were necklace-like rows of them — six to eight 

 together ; the contents consisted of colourless protoplasm, with 

 one or two nuclei. The swollen portions were generally sur- 

 rounded by a thick mass of mycelium-threads, so that they became 

 obscured ; the swellings were globular, about -g-oVo" ^^ diameter, 

 their size bringing them at once into marked contrast with the 

 slender mycelium-threads which produce them. Dr. McNab did 

 not hazard any conjecture as to their nature or function, but 

 stated that they seemed somewhat to resemble the " Macrogonidia" 

 of Penicillium figured by Hallier in his ' Phytopathologie,' PI. v, 

 fig. 31. 



Besting-s pores of Peronospora infestans exhibited. — On the part 

 of Prof. Thiselton Dyer, who kindly sent the material, Mr. 

 Archer exhibited some of the original diseased potato-specimens 

 in which Mr. Worthington Smith had made his recent very inter- 

 esting discovery of the resting-spores o£ Peronospora infestans. 

 On looking over the slide, only one example of the " antheri- 

 dium " was to be noticed in actual contact with an oogonium, 

 but even in Mr. Smith's experience this was rare to find. 



Fructification in Polysiphonia. — Dr. McNab showed a minute 

 branch of Polysiphonia fastigiata, gathered at Seapoint in July, 

 which showed the young cystocarps, and in two of them the 

 minute lateral structure was developed, which he identified as 

 the trichogyne. On the same portion of Fucus nodosus he had 

 met with a Polysiphonia bearing antheridia on same plant and 

 tetraspores on another. 



Structure of Spines in FJchinothrix Desorii. — Mr. Mackintosh 

 exhibited transverse sections of the spine of Fchinothrix Desorii, 

 Peters. The spines of this species approach those of E. calamaris 

 much more closely in structure than E. turcarimi, both of which 

 have been described in these Minutes. In E. Desorii there is a 

 wide central cavity surrounded by a narrow zone of network 

 through which pass the stems of the solid pieces, which are very 

 elongated, with concave sides, and usually globular terminations. 

 The stems are joined by broad transverse bars, and in some cases 

 there are the remains of a network which, extended over the 

 central cavity. Mr. Mackintosh was indebted to Prof. Peters, of 

 Berlin, for opportunities of examining the spine of this species. 



Sections of Obsidian from Ascension Island were exhibited by 

 Prof. Hull. 



New Species of Euglypha. — Mr. Archer exhibited the test only, 

 as the sarcodic portion had ceased to live, of what seemed doubt- 

 less a new species of Euglypha : — Test minute, but of variable size, 

 ovoid, compressed ; when old, brown, or reddish in colour (quite as 

 highly tinted as Arcella vulgaris), sometimes seeming to incline 

 a little to a purplish tint, when young, colourless ; in the highly 

 coloured examples paler near the opening; hexagonal facets 

 extremely minute, elongate, test not prolonged into a " neck," its 



