284 PROCEEDINGS OF THE SOCIETY. 



and even if we had a means of telling how far the aperture of the objec- 

 tive had been reduced by stopping down, there would be a considerable 

 margin of error in endeavouring to determine the size of objects by such 

 means. 



The other point which had struck him was in connexion with 

 Mr. Nelson's remarks on the dark-ground illuminator : " Owing to 

 defects in some dark-ground illuminators it is not possible to obtain a 

 dark field when the objective has a wide angle." 



He considered that this statement might be criticized. The whole 

 principle of the dark-ground illuminator was that the total aperture of 

 the illuminator should exceed that of the objective, a central cone being 

 blocked out, so that with annular illumination of wide angle from the 

 illuminator refracted rays from the object would alone enter the objective. 



A second paper by Mr. E. M. Nelson on " Some New Objectives and 

 Eye-pieces by R. Winkel of Gottingen," as well as another by the same 

 author on " The Variable Microscope," were read by Mr. Shillington 

 Scales. 



No remarks being offered on these communications, the President 

 returned the thanks of the Society to Mr. Nelson for his papers. 



Owing to the lateness of the hour the paper by Senor Dominga 

 de Orueta on "Apparatus for Photomicrography with the Microscope 

 standing in any Position, especially in Inclined Position," was postponed 

 till the next Meeting, and Mr. James Murray's paper on " Australian 

 Rotifers, collected by the British Antarctic Expedition, 1909," was taken 

 as read. 



A letter from Mr. F. W. Gordon was read by Mr. Shillington Scales, 

 enclosing a cheque for £5 as an expression of his sympathy with the 

 proposal which had been made by their Ex-President to supply the 

 Microscopical Society with a fitting number of show cases for their 

 exhibits, and promising a further subscription if the late President's 

 other suggestion, to acquire a really typical collection of slides that can 

 be used by those desiring information, be carried into effect. 



Mr. Shillington Scales hoped that Mr. Gordon's donation would have 

 the effect of stimulating other Members of the Society to follow his 

 excellent example. 



The next Meeting was announced for April 19, when a paper would 

 be read by Mr. E. J. Sheppard, on " The Reappearance of the Nucleolus 

 in Mitosis," and Mr. E. J. Spitta would give a demonstration of " Low- 

 power Photomicrography with Special Relation to Colouring Methods." 



The following Instruments, Objects, etc., were exhibited : — 



Mr. W. R. Traviss : — Two Objectives, h in. and J in. with iris, described 

 in Mr. Nelson's paper. 



New Fellows : — The following were elected Ordinary Fellows of 

 the Society : — Sidney Howard Browning, Francis Martin Duncan, 

 Robert Ludwig Mond, H. E. Ranken, Alfred J. Sewell, Mrs. Rose Haig 

 Thomas, Dr. Ralph Vincent, Professor German Sims Woodhead. 



