( 4 ) 



Summary of Gubrbnt Rbsbabohes, &c. — continued. 



TAOZ 



Influence of Antiseptics on Mucor ,. 284 



Two New Mucorini 284 



New Coloured Bacterium 284 



Cultivation of the Bacterium of Foot-Rot 285 



Influence of Concussion on the Growth of Bacteria ^ 286 



Long Life of Anthrax Germs : their Preservation in Cultivated Soils . . 286 

 New Disease due to the Action of the Saliva of a Child who died from 



Hydrophobia .. .. .. 286 



Nature of Malaria 287 



Animal Nature of Myxomycetes ., .. 288 



Cell-nucleus in Algx 289 



Formation of Endogenous Shoots in Algie .. . . 289 



Spiral Phyllotaxis in Floridese 290 



Sargassum and the Sargasso Sea 290 



Spermothamnion torulosum 291 



Genetic Connection of certain Unicellular Phycochromaceie 291 



Crystalloids of Marine Algie 292 



MiCBOSCOPY, &c. 



Griffith Club Microscope (FigB. 39-il) 293 



Swiff s Students Microscope (Wale's ModeT) (Figa. i2-U) 296 



Abbe's Stereoscopic Eye-piece (Fig. 45) 298 



Watson^s Mechanical and Botating Sta^e (Fig. iG) 300 



"Butterfield" Gauge of Screw for Objectives (Fig. il) 301 



Homogeneous-immersion Objective with extra Front Lenses 301 



Murray and Heath's Pokirizing Apparatus (Figs. 'is and i9) 302 



Notes on Aperture, Microscopical Vision, and the Value of wide-angled 

 Immersion Objectives : — 

 I. The Aperture Theories. — Apertures exceeding 180° angular in 

 air. — The true notation for Aperture. 



1. The two Theories of Aperture 304 



2. " Dry " and " Immersion " Objectives (Fig. 50) . . . . 305 



3. Definition of ^^ Aperture" (Figs. 51-5S) 807 



4. Increase of Aperture with the increase in the density of the 



Medium. — Apertures exceeding 180° angular in air (Figs. 



54 and 55) 308 



6. Tlie Photometrical Test. — Supposed Identity of the Hemi- 

 spheres in different Media (Figs. 56-62) 311 



6. The " Resolution" Test 316 



7. The " Angular Grip" 318 



5. Numerical Aperture (Figa. 63 and Gi) 321 



II. Angular-Aperture Fallacies. 



1. The Hemisphere Puzzles 326 



(si) The Convex Hemisphere (Figa. 65-67) 326 



Ih) The Concave Hemisphere (Fig. 68) 328 



(c) The Hemisphere as a Condenser (Figs. 69 and 70) 329 



2. Illumination Fallacies (FigB. 71-73) 330 



3. Power of the Plane Surface of a Lens (Fig. 74) .. .. 332 



4. The Diagram Fallacy. (_The Stokes immersion and the 



ShadboU dry Objectives) (Figs. 75 and 76) ., .. ,. 333 



5. Fallacies in Practical Construction 337 



6. " Not Image-forming Rays" (Fig. 77) 338 



7. " Only a Question of Nomenclature" 340 



III. Photometrical Questions connected with Aperture. 



1. Difference of Radiation in the same Medium (Figs. 78-82) 341 



2. Increase of Radiation in Glass, Oil, &c. (Figs. 83-90) , . 343 

 IV. Microscopical Vision and the Delineating Power of Objectives. 



1. The Abbe Theory of Microscopical Vision (Figs. 91-107) 348 



2. The Delineating Power of Objectives and Aperture (Figs. 



108 and 109) 356 



V. The Value of wide-angled Immersion Objectives 359 



Aeroscopes ^^1 



Slip-cleaning Instrument 362 



"Opaque" Illumination by the Vertical Illuminator 362 



Amphipleura pellucida by Reflected and Transmitted Light 363 



ThelateF.A.Nci)eH 364 



Proceewkgs of the Sooiett (Fig. 110) 366 



