19 1 2 IrisJi Societies, loi 



the central disc of clialcedony represented the periodic movement of the 

 chemical action. This mode of origin has been snggested by Professor 

 Sollas for certain banded flints, but in the case of Beekite Mr. Strachan said 

 he had particular pleasure in announcing its formation as the first mineral 

 growth definitely " confessing its history " as an osmotic periodic growth. 

 The lecture was illustrated by numerous specimens, microscopic slides, 

 photographs and chemical precipitates of opaline silica in gelatine showing 

 the concentric periodic rings produced in the laboratory. 



An interesting discussion followed in which Robert P>ell, S. Wear, K. 

 May, and the Chairman took part. 



April 3. — The concluding lecture of the session to the junior section 

 took place on 3rd April, when Joseph Maxwell, J. P., gave an instructive 

 account of " Pond Life." In the absence of Robert Patterson, M.R.I. A. 

 (chairman of the section), George Donaldson presided. The lecturer com- 

 menced by saying that most people had the idea that ponds were full of 

 nil kinds of unwholesome and loathsome objects, but he hoped in the 

 course of his address to dispel that idea and to show there were animals 

 and plants living in ponds quite as beautiful and perhaps more interesting 

 than those leading a terrestrial life. The apparatus used for collecting 

 ]iond life was exhibited and explained, and hints given as to how such 

 apparatus could be easily manufactured at home at a very small cost. 

 By the aid of a large series of lantern-slides Mr. Maxwell described the 

 structure and habits of many pond inhabitants, commencing wath the 

 vegetable kingdom, and continuing by treating the animal kingdom in 

 systematic sequence. At the conclusion of his address the lecturer gave 

 a microscopic display, showing many of the objects he had mentioned 

 living. Mr. Maxwell has kindly undertaken to lead an excursion to the 

 Lagan district and show how^ aquatic animals and plants can best be 

 obtained and prepared for examination. 



DUBLIN NATURALISTS' FIELD CLUE. 



March 12. — The Club met in the Royal Irish Academy House, R. LI. 

 Praeger in the Chair. The programme of the meeting consisted of a 

 number of microscopic exhibits and demonstrations. 



R. Southern showed a new Gephyrean belonging to the genus Phasco- 

 losoma, dredged in 700 fathoms off the west coast- of Ireland. Its more 

 characteristic features were pointed out, especially the peculiar structure 

 of the papillae on the skin, and these were further illustrated by means 

 of transverse sections of the skin. 



T, Hallissy gave a short description of the petrological microscope, 

 and indicated some of the methods by which crystals can be recognised 

 from their behaviour towards polarized light. He showed slides of a 

 tvpical holo -crystalline rock — microgranite from the Wicklow Gap ; also 

 a typical glassy rock — pitchstone from near Barnes Lough, Co. Donegal ; 

 and a fine-grained sandstone from the southern slope of Croaghmorc, 

 Clare Island. 



