385 



MEETING 



Held on the 17th of April, 1907, at 20 Hanover Square, W. 

 G. C. Karop, Esq., M.R.C.S., in the Chair. 



The Minutes of the Meeting of the 20th of March, 1907, were 

 read and confirmed, and were signed by the Chairman. 



Mr. Barnard exhibited and described the advantages of the Mercmy 

 Vapour Lamp, used as an ilhiminant in connection with the Microscope. 



Mr. F. W. Watson Baker, on behalf of Messrs. Watson and Sons, 

 exhibited a new form of expanding stop, for use with a substage con- 

 denser, to enable a dark ground to be produced with objectives of dif- 

 ferent apertures. It was made to fit into the carrier of an ordinary 

 Abbe illuminator. 



The Chairman thought this a most ingenious device, which was likely 

 to be of great value to any one who wanted to use stops of different 

 sizes. 



Mr. A. Earland — who had arranged an exhibition of slides of 

 Foramiuifera — said that while on a former occasion he had exhibited 

 specimens selected for their beauty only, he had this time endeavoured 

 to combine elegance of form with other points of interest. He then 

 proceeded to describe the exhibits, which consisted entirely of typical 

 " arenaceous " Foramiuifera, and were arranged in a series intended to 

 show the varying degree of skill and " selective power " exercised by the 

 animal in the construction of its test or shell. 



On the motion of the Chairman, votes of thanks were passed to 

 Mr. Barnard and Messrs. Watson for their exhibits, to Mr. Earland for 

 his very interesting and instructive remarks upon the exhibition he had 

 arranged ; also to Messrs. C. Baker for having provided the Microscopes 

 under which Mr. Earland's slides of Foramiuifera had been shown. 



Mr. E. M. Nelson's paper, " On the Podura Scale," was read by 

 Dr. Hebb — copies of the figures in illustration being drawn on an 

 enlarged scale upon the board by Mr. Scourfield. 



The Chairman thought it was very refreshing to hear a paper on an 

 old subject like that of the Podura scale, which, however, did not appear 

 yet to have been worked out fully. 



Mr. Conrady thought that Mr. Nelson was under a mistake as to the 

 cause of the effect produced by looking at an object in contact with the 

 cover-glass, because the scales were in this case not in actual contact 

 with it, but there was a very thin layer of air between, which allowed the 

 light to pass through — which was known as Stokes' layer. Also in his 



