DUBLIN MICROSCOPICAL CLUB. 85 



coast. The wood is completely silicified, and the details of its 

 structure are very perfectly preserved. From the even distribu- 

 tion of the fibro-vascular bundles the fragment must have formed 

 part of a trunk of large size, and this was tolerably conclusive 

 evidence of its having belonged to a palm. Mohl had, however, 

 shown that the structure of palm stems could not be correlated 

 with their other characters,' so that here our information stopped, 

 linger had, indeed, based a genus Fasciculites upon fossil palms, 

 in which the parenchyma was arranged in a somewhat radiate 

 manner round the bundles, as is the casein the present specimen ; 

 but this was manifestly a valueless character, and Schimper had 

 transferred all true palm stems to Palraacites. 



Dr. E-. McDonnell showed various epithelial structures, which 

 he had prepared from the frog and other subjects, to illustrate 

 the value of the nitrate of silver process in rendering the delicate 

 cell-walls evident under the microscope, the nucleus becoming 

 stained by the use of the carmine solution, thus rendering the his- 

 tological features readily discernible. 



Mr. Archer showed, some conjugated examples of Spirotcenia 

 truncata (ejus), brought from Glencar, Co. Kerry, on a recent brief 

 excursion in company with Dr. E. P. Wright. This minute 

 species is a rare one in itself, and the zygospore had only once 

 before been seen, and then first recorded by Mr. Archer, along 

 with the then likewise first-known instance of the conjugation in 

 its larger and far more common relative, Spirotcenia condensata 

 (' Quart. Journ. Micr. Science,' vol. vii, n. s., p. 186) . Hence the pre- 

 sent gathering, showing some dozen or two of examples of the con- 

 jugated state (in S. truncata), was of some interest. Mr. Archer 

 regretted, however, he had been unable to detect any less advanced 

 or earlier condition of the conjugative process in this species than 

 that he had figured. In case, however, this state should be met with 

 by others, he ought to mention that the figure of the zygospore 

 published is unfortunately too stilf, and the angular lobe-like pro- 

 jections rather too symmetrical ; they are, in fact, somewhat 

 irregular, and less pointed at the apices ; but the colour and 

 general appearance, with the still appended empty parent cell- 

 walls, are correct. These conical or sub-triangular projections 

 seem to be void, of a straw colour, and the spore itself is a 

 green orbicular body, posed in the centre of the general cavity. 

 Such a special outer covering to the spore, the latter contracted 

 into a smaller body in the centre of the cavity, leaving an inter- 

 space between it and the former, has a parallel in certain other 

 species in Conjugatae, e.g. Docidium Ehrenbergii, Tetmemorus 

 granulatus, Mougeotia glyptosperma (de Bary), &c. The present 

 species had never before been exhibited, with its zygospore, to 

 the Club, and the latter forms a singular-looking and certainly 

 pretty little object. 



Amongst other of the rarer Desmidiese taken on the same 

 occasion (from Cos. Kerry and Cork) were presented examples of 

 Tetrachastrum pinnatifidum ; this is a very rare form, and, when 



