246 



dine over styrax, but he found that it was difficult to keep. 

 The specimen shown had crystallized after the first month, but 

 when remelted it was quite restored. 



Mr. Karop said that what remained of the Whomhoides in his 

 slide certainly came out very well. 



The Chairman said that quinidine was a substance which 

 seemed to him to have the greatest possibilities ; it certainly 

 was the most brilliant resolving medium with which he was ac- 

 quainted, and he hoped that all who could work at it would do 

 their best to try and find some means of securing its permanence. 



Mr. Morland said that if after a time it was found to re- 

 crystallize all they had to do was to warm it up again, and it 

 would be all right. 



Mr. C. L. Curties pointed out the necessity for not "ringing" 

 slides so mounted, otherwise when warmed the varnish would be 

 likely to run in. 



The Chairman exhibited and described a new form of sphero- 

 meter, made from his own designs, for the purpose of measuring 

 the curvatures of lenses of various sizes. 



Mr. Ashe being unable from cold to read his paper " On the 

 Determination of Optical Tube Length," it was read by the 

 Secretary. 



The Chairman thought this was a valuable communication 

 giving them an original and very simple formula for getting the 

 equivalent of the tube length, and he would advise every micro- 

 scopist to write it on the first page of his note-book. It fur- 

 nished them with a ready means of getting the arithmetical 

 equivalent, and from that they could always ascertain the power 

 of an unknown objective. The only previous way was to find 

 the diameter of a projected image at a great distance — say five 

 feet — by which any small error in the distance would be 

 absorbed; but the manner suggested by the paper was very 

 much more simple, and it had only to be known and appreciated 

 to ensure its being used every day. 



Mr. Western read his " Notes on Rotifers," illustrating the 

 subject by drawings on the black board. 



Mr. Bryce congratulated Mr. Western on having been able to 

 clear up some doubtful points, and thought it was a great help 

 to those who took an interest in such matters to get them so 

 nicely described. 



