CORRESPONDENCE. ■ 139 



drical forms with screw-collars, the pattern of which should be pre- 

 viously assigned, and identification seciu'ed either by a small engraved 

 motto or high numbers. The motto with the maker's name to be en- 

 closed in a sealed envelope, to be opened by the committee after its 

 final award. The definition to be tried both with full and reduced 

 apertures, with long and short tubes and approved eye-pieces (deep), 

 C, D, E, F of ascertained focal length.] 



Q) For Eesolution. 



(2) For Penetration or depth of focus. 



(3) For Magnifying Power. 



(4) For Spherical and Chromatic Aberration. 



(5) For Angular Aperture. 



Illumination to be entirely centrical through a l^-inch objective 

 condenser, limited to 10° aperture, used obliquely or directly. 



I cannot but think that some such scheme would greatly benefit 

 microscopical science, and settle some necessary axioms about which we 

 are very much at sea at the present moment. 



I am yours, very faithfully, 



G. W. KoYSTON-PlGOTT. 



P.S. — I propose at the next meeting to exhibit and illustrate the 

 little instruments alluded to in this number, should the President 

 approve of this suggestion. 



English Microscopists. 



To the Editor of the ' Monthly Micrcscopical Journal.^ 



4, St. Martin's Place, Feb. 16, 1871. 



SiK, — You have done me the honom- of indirectly referring, in 

 your January number, to certain experiments of mine with infusions 

 of milk. If you had not done so, I should not have noticed the 

 criticisms of the anonymous writer in the American journal from 

 which you quote. 



I quite agree with my critic that amoeba is "an object about the 

 nature of which very little is known," but I trust I am not so ignorant 

 as not to know amoeba when it shows itself under the microscope. Nor 

 is it likely that I should mistake for infusoria the so-called oil globules 

 of milk, the movement of which I have watched too often to be thus 

 deceived. It appears to me to be very objectionable for writers to 

 thus broadly, and in reality without the slightest ground, endeavour 

 to throw discredit on the observations of others. Nor is it good 

 taste, to sa,y the least, to assume that all observations but those which 

 agree with the notions of American microscopists are made with 

 " inferior instruments," as compared with Mr. Holman's " good 

 objective." The italics are not mine. 



I am, sir, yours obediently, 



C Staniland Wake. 



