376 PEOCEEDINaS OF THE SOCIETY. 



it would, he believed, be found that the greater refinement of defini- 

 tion, incident to more perfect achromatism, must, when combined with 

 the present enormous apertures, yield, in future research, results still 

 further in advance. He congratulated Prof. Abbe, and microscopists 

 in general, on the happy combination from which so much might be 

 expected. 



Mr. E. M. Nelson said that the opportunity had been afforded him 

 by Mr. Crisp of trying the other objective. He first used it upon 

 P. angulatum, and found that it gave a very beautiful picture. He 

 was able to use a larger cone, and to see much more clearly the 

 small bar of silex which he had mentioned on a former occasion. On 

 trying Isihmia nervosa with the whole aperture of Powell's condenser 

 and a solid cone, the secondary markings came out remarkably well, 

 and he was able to trace a fracture most beautifully. He next tried 

 Coscinodiscus, and here there was a great change observed, for instead 

 of the silex coming out a pinkish colour, as usual, it was grey. He 

 then examined Amphipleura pellucida with an oblique beam of light 

 (1 • 4 N.A.). The diatom was mounted in Prof. Smith's medium, and 

 he never saw such a picture — so sharp and distinct. 



The President said that they had been for some time anticipating 

 the pleasure of seeing these lenses, and particularly so after what 

 was mentioned about them at their previous meeting, but it was a 

 pleasant surprise to him to find them in London on his arrival that 

 afternoon. It was a matter of much satisfaction to have the opinions 

 of Mr. Stephenson and Mr. Nelson, and still more so to hear from 

 them that the good reports which had already reached them had not 

 been exaggerated. There was no doubt a great field opened up by 

 this new departure, and he might say for himself that, although he 

 had spent a great deal of money in obtaining the most perfect lenses 

 possible for the purposes of his own investigations, he should be very 

 glad to avail himself of any advantages which might be offered by 

 the new objectives. 



Mr. A. D. Michael gave a resume of his paper " On the Life- 

 history of an Acarua, one stage of which is known as Lahidophorus 

 talpse ; and on an unrecorded species of Disparipes" The subject was 

 illustrated by drawings upon the black-board, and by mounted pre- 

 parations exhibited under Microscopes. 



The President, in expressing the thanks of the Society for this 

 communication, said it was very pleasant to see the earnest work 

 which was being done around them, especially when it was so successful 

 as it was in the hands of Mr. Michael. 



Mr. W. C. Meates' note on ' A new Medium of High Eefractive 

 Power for Diatom Mounting ' was read (supra, p. 357). 



Mr. A. Y. Moore's slides of stained Amphipleura pellucida were 

 exhibited, and the advantages of staining as applied to diatoms 

 discussed, Mr. Stephenson pointing out that diatoms had been stained 

 many years ago, but that the result had not been found sufficiently 

 satisfactory to warrant a repetition of the experiment. 



