PROCEEDINGS OF THE SOCIETY. 1105 



daughter, Lad recently been presented to the Linnean Society, while 

 an appreciative memoir has been published * by his friend Prof. 

 Allruan. 



Mr. dirties exhibited several of the new apochromatic objectives 

 (with a series of eye-pieces) made of the new kinds of glass from the 

 Jena manufactory, which were examined by the Fellows with great in- 

 terest ; the very high eye-pieces which they carried without " breaking 

 down " being a special subject of comment. 



Prof. Abbe's paper " On Improvements of the Microscope with the 

 aid of new kinds of Optical Glass," was read (post). 



The President said he had been greatly interested by the explana- 

 tions given in Prof. Abbe's paper, and the Fellows would doubtless 

 be glad to know that the 1/12 in. objective was in the room that 

 evening, and fitted to a Microscope with a suitable eye-piece, so that 

 its perfection could be seen by those present. 



Mr. Cheshire inquired whether the new kinds of glass could be 

 bought in this country, and if full particulars could be obtained as to 

 their respective indices, dispersive powers, &c, so as >to make it 

 possible for similar objectives to be made here in due course by 

 English opticians, suitable for their own instruments ? The objectives 

 shown that evening gave results which he could only describe as most 

 magnificent. 



Mr. Crisp said that a very full and complete descriptive catalogue 

 had been published, in which all particulars were given as to the 

 optical qualities of the glass. Indications were given as to the best 

 kinds to be used in the construction of objectives for telescopes, &c, 

 but with regard to Microscope objectives, the subject was dismissed 

 with the remark, that " it must be left to the skill of the practical 

 optician to choose the most suitable from the above series. The new 

 objectives show what can be attained in practice." It was of course 

 quite fair to keep such a matter as a trade secret, and it could not be 

 expected that opticians should publish their trade methods and 

 formulae for the benefit of their business competitors. 



Mr. T. B. Eosseter's paper " On Trichodina as an Endoparasite," 

 was read by Prof. Bell. The author described a very careful series of 

 observations, by which he had established that this Infusorian hitherto 

 only known as an Ectoparasite, infested the urino-seminiferous organs 

 of newts (supra, p. 929). 



Dr. Crookshank said it would perhaps be remembered that during 

 the last Session he read before the Society a paper on Photomicro- 

 graphy (ante, p. 735), in illustration of which he then showed a 

 number of photographs of bacteria. He had done some further work 

 in that direction, and had brought with him a new negative which he 

 was anxious the Fellows should examine, because it was one in which 

 the flagella of a Vibrio were very distinctly shown. It would, no 

 doubt, be known to most of the Fellows that some persons had 



* Nature, xxxiv. (188G) pp. 387-9. 

 Ser. 2.— Vol. VI. 4 



