37 



Spirorlis nautiloides Mr. F. W. Andrew. 



Philodina erythropthalma ... ... ... Mr. J. Badcock. 



Epistylis anastatica ... ... ... ... ,, 



Cristatella mucedo ... ... ... ... Mr. W. G. Cocks. 



Section of stem of Carex paludosa ('Sedge) ... Mr. C. G. Dunning. 



Marine mite. Halacarus, sp. ... ... ... Mr. H. E. Freeman. 



Larva of Labanus (Gadfly) Mr. J. D. Hardy. 



Stentor Mulleri ... ... ... ... ... Mr. T. J. McManis. 



Myohia chiropteralis, Q and g n.s. ... ... Mr. A. D. Michael. 



Larva of an eutozoon ... ... ... ... Mr. E. M. Nelson. 



Gonium pectorale ... ... ... ... Mr. C. Le Pelley. 



Fredericella sultana ... ... ... ... „ 



Section of scale from Sciadopitys verti- 



cillata ... 

 Scale leaves of ditto 



Fredericella sultana Mr. C. Konsselet. 



Trans, sec. Tongue of Cat Mr. F. Steele. 



Diatom, Triceratium A 'ormannianum ... ... Mr. G. Start. 



Clava squamata ... Mr. A. Wildy. 



Attendance — Members, 66 ; Visitors, 4. 



Mr. J. W. Eeed. 



» 



May 9th. — Conversational Meeting. 



A demonstration on polarized light was given by Mr. Charles Stewart, 

 F.L.S., F.R.M.S., &c, who observed that, as it was some 20 years since he 

 had worked at the subject, he had hoped to have had an opportunity of 

 revising his knowledge, but a pressure of business had borne especially 

 hard upon him, and he really had not had an opportunity of doing what he 

 would have liked to do. 



He purposed, as this was a demonstration, to first explain shortly the 

 various arrangements he had brought to illustrate the theory and use of 

 polarised light. 



Having briefly explained the generally accepted theory of light, as con- 

 sisting of certain vibrations of the ether caused by the active molecules in 

 the source of light, as, for example, the flame of a lamp, and illustrated his 

 remarks by diagrams on the blackboard, he passed on to consider what 

 changes were found in light when modified by polarization. 



The vibrations being restricted to some one particular direction, causing 

 lineal or plane polarization, the beam w r ould display distinct sides, one in 

 the plane of its vibrations, and the other in a plane at right angles to the 

 first. 



The simplest form of table polariscope for examining light was a series 

 of thin glass plates, the lowest one blackened at the back, a piece of 

 ground glass being placed between the lamp and the bundle of plates to 

 diffuse the light, and a piece of clear glass being placed between the bundle 

 of plates and the observer, and forming an inclined support on which the 

 films of selenite and mica could be conveniently placed and manipulated. 



