DUBLIN MICROSCOPICAL CLUB. 215 



with Navicula didyma, sporangia! variety, W. Sm., ' Brit. Diat.,' 

 vol. i, t. xvii, f. 154, a. This bears a strong resemblance to iV. 

 Smithii, \sx.fusca, Greg., so that it is not surprising that some 

 should have identified it with the last-named species. A close in- 

 spection, however, of the peculiarities led him to the conclusion that 

 it is quite distinct. The central panels in both are somewhat 

 rhombical, and the striation in this portion very similar, apparently 

 costate ; JS^ai'icula fusca, indeed, in some aspects, appears slightly 

 incurved at the sides, but this is plainly constricted. In the former 

 the general striation is moniliform — in the latter it consists of some- 

 what elongated lines, and much coarser than the other species. 



Nostocliaceous filaments in tissue of Azolla, exhibited. — Professor 

 M'Nab exhibited an illustration of the presence of Nostochaceous 

 filaments in the tissue of higher plants, an occurrence recently 

 drawn attention to by observers (Keinke and others), as exemplified 

 by Azolla. These he had extracted from the tissue and placed 

 under the microscope, stating that, on looking over the collection he 

 possessed of different ^zoZ^«-species, all had shown him the presence 

 of these algae within their tissue, adverting also to the fact that, 

 whilst these had for some time been noticed, they had been by certain 

 observers interpreted as in someway connected with the reproductive 

 apparatus of the Azolla. The presence of foreign algse forms within 

 the tissue of higher plants had lately acquired a double interest, 

 that which attached to their living and seemingly flourishing in so 

 unexpected a habitat, as well as that which these "parasitic" algse, 

 so called ad interim, had in relation to the new theory of 

 the nature of " lichen-gonidia " propounded by de Bary and 

 Schwendener. 



Illustrations of the Reproductive Apparatus in Marchantieai. — 

 Dr. Moore exhibited plants of Morckia hibernica, Grottsche, and 

 Petalophyllum Ralfsii, Gottsche. The latter had the male and 

 female flowers in good condition. Groups of young archegonia 

 i-eady for impregnation, and some impregnated, were shown. 

 Dr. Moore mentioned that he had seen numbers of the thread-like 

 bodies like spermatozoa floating about among the archegonia, but 

 could not observe that they entered at the apex of those bodies. 

 The observation was made with a moderately good French -i object 

 glass. On another slide Dr. Moore had the male flowers of Lunu- 

 laria vulgaris, which, he observed, were in good condition at this 

 period of the season. He further observed that when the male 

 flowers arc fully ripe, if the plant be put into a pan or saucer and 

 covered over with a pane of glass, a quarter of an inch or so apart 

 from the surface of the plant, the glass, though well cleaned when 

 put on, will after a few days become discoloured. If the substance 

 wliich causes this be gently scraped off and put on a slide with a 

 little water, and covered with a covering glass, it will be found to 

 consist chiefly of the ovate antheridia, which led him to conjecture 

 that those minute organisms are ejected from their cavities on the 

 surface of the thallus by a jerk. He had not seen this take place, 

 but he could not account otherwise for this being on the surface of 



