1892.] MICROSCOPICAL JOURNAL. 139 



evident fact that the English type has entered by far tlie most 

 largely into our experience thus far. Without forgetting that 

 where the \yisdom and experience of continents are concerned, the 

 opinions of single indiyiduals are of little importance, the writer 

 could not do justice to the title of this paper \yithout giving his 

 ••impressions" on this very interesting phase of the subject. 

 While a user of the English style for more than thirty years, and 

 naturally with strong preposessions in its favor and still satisfied 

 with it, he must admit that the neat and unpretentious continental 

 stands of the smaller and more simple grades become more at- 

 tractive with every increase of acquaintance. It would be diffi- 

 cult to find anything more tempting or practical for student's 

 laboratory work (exclusively) than the beautiful little stands ex- 

 hibited by all the French and German makers, though some of 

 the small American and English stands still seem to be equally 

 available. On the other hand, the larger stands of the continental 

 type, with elaborate adjustments and numerous accessories, 

 always produce the feeling that, notwithstanding their ingenious 

 designs and great efficiency, they are unfortunately clumsy and 

 soniew'hat overloaded, their traditional compactness being main- 

 tained at the cost of some unnecessary inconveniences. The pos- 

 sibilities of the English-American stand seem to be not yet realized 

 on the continent ; but the writer will venture the prediction that 

 there will be a revolution in this respect some time befoie the 

 next tricentennial. The reaction has evidently commenced 

 already in respect of accessories and incidental refinements of de- 

 taij. Such microscopical aids and comforts as mechanical stages, 

 elaborate sub-stages and Sub-stage condensers, iris diaphragms 

 and rapid nose-pieces, which we have been using for a genera- 

 ation, more or less, with great satisfaction, but which we have 

 meanwhile heard constantly denounced by partisans of the con- 

 tinental method as needless luxuries and distracting toys, all these 

 we now see introduced and given a proper prominence by the 

 best continental makers. 'Tis well. 



As to objectives, the progress of the present da}- evidently cen- 

 ters around or stands in comparison with, the apochromatic sys- 

 tem. Of the success of the system there is no longer a reasonable 

 doubt, either as a scientific or as a commercial question. Char-, 

 acterized by the employment of new varieties of glass, of extra- 

 ordinary optical properties, manufactured at Jena, and by the 

 substitution of tluorite (natural fluor spar) for crown-glass in sev- 

 eral of the lenses, it corrected spherical and chromatic aberration 

 to an extent not before attained. Brought into existence by the 

 researches and experiments of Abbe and Schott. and first success- 

 fully introduced at the Zeiss factory, in 18S4, it is now adopted for 

 their highest grades of objectives by all the above-named makers, 

 except perhaps Watson ; and new series or varieties are being con- 

 stantly introduced.* The resolution of Amphipleiira pellucida 



* Near the close of the exposition, after the report on ;i wards was adopted and closed, a new 

 i-i2th (2 mm.) was received from Nachet and informally examined by the jury, with the re- 

 sult of calling out from them a special note of commendation. 



