DUBLIN MICROSCOPICAL CLUB. 105 



Passalurus amliguus was exhibited by Mr. Booker. 



A minute Bhizopod belonging to the genus 3Iicrogromia, Hertwig 

 and Lesser, probablg distmctfrom M.socialis (Archer), Hertwig and 

 Lesser. — Mr. Archer desired to mention that, in connection with 

 the plant he had formerly described (now as is proven erroneously) 

 as a species of Dictyosphserium, Niig., under the name of Z). con- 

 strictum, and of which he had shown the conjugated state at the 

 meeting of the Club in May last, he had now discovered that 

 the little pear-shaped colourless body he had so long noticed 

 accompanying that alga and imbedded in its mucous matrix, was 

 not, as he had once conjectured, in any way necessarily belonging 

 to the alga, but was a veritable Ehizopod, and in fact, as it 

 would seem, appertaining to the genus Microgromia, a genus 

 founded by Hertwig and Lesser on his own Gromia socialis. This 

 little organism, found along with the little alga referred to, had 

 long puzzled him ; it might or might not have some genetic con- 

 nection with the alga — it might be anything, in fact. But tliere it 

 was, a little pyriform, nearly " colourless " (but yet showing a very 

 slight bluish tint) inert body, a frequent concomitant of the alga. 

 In the very last example he had seen (strange to say, very shortly 

 after Mr. Archer had taken the gathering yielding the conju- 

 gated specimens of the alga, it had abruptly disappeared from its 

 site !) he had, however, noticed its possession of pseudopodia 

 and a whitish nucleus (like that oi Microgromia socialis), which 

 latter took a high tint on the application of Beale's carmine fluid. 

 Its linear dimensions are scarcely more than one third those of Mi- 

 crog. socialis, its pseudopodia very slender, branched, granulifer- 

 ous, their movements verj/ slow. If the alga with which this little 

 Ehizopod consorts should again make its appearance, Mr. Archer 

 hoped to obtain more examples and give it a closer study than be 

 was able to do with so limited material. 



Bacteria (Bacillus) habitually forming a Nidus in Mucous In- 

 vestments of Algce.- — Mr. Archer directed attention to an alga of 

 which he had wished for specimens at the May meeting in order 

 to have contrasted it with the so-called Dictyosphserium, referred 

 to above, but he then had no examples at command : this was Cos- 

 mocladium Saxonicum, de Bary, a plant, though widely distributed, 

 very rare in its occurrence. This species, however, he had before 

 shown to the Club, and he now merely brought it forward as a 

 good example of a fact he had found pretty generally noticeable 

 in algae surrounded by a mucous envelope, but he likewise 

 thought not generally (if at all) noticed. This was that im- 

 bedded in a vertical or radiant position in the matrix occurred 

 numerous bacteria (Bacillus-form), which from their rather regular 

 disposition imparted a radiantly striate appearance to the sur- 

 rounding halo of mucus. Similar occur too in the mucous envelope 

 of very many Desmidiese as well as other algse, and give that 

 striate appearance often noticeable ; in fact, the depth and density 

 of this mucous investment seems to a certain extent specific in 

 various Desmidiese, and even the amount of striation due to the 



