27 



att gifva dylika bilder, kallas definition eller definitions- 

 formag a*). 



Hvilket af dessa bada objectiver, hvardera i sin riktning 

 uppdrifvet till den hogsta mojliga fullkoinlighet pa den andras 

 bekostnad, har foretradet? I optiskt hanseende aro bada otill- 

 fredsstallande och ensidiga, i praktiskt bada anvandbara. 

 Behofvet af ett penetrerande objectiv ar dock i allmanhet 

 oandligt mindre an behofvet af ett definierande, ty till defini- 

 tionsformagan sta vi i forbindelse. for niistan alia, bade aldre 

 och nyare mikroskopiska upptackter, och mikroskopien maste 

 inrymma at henne framsta rum met; till penetrationsformagan 

 for upptackten af nagra strimmor, punktformiga upphojningar 

 och andra configurationer pa en del Diatomeskal, — resolve- 

 ringen af ett storre eller mindre antal af grupperna pa No- 

 berts Probetiifelchen ej att forglomma**). 



*) Hartnack fabricerar 2:ue serier ordinara objectiver fran och tned 

 n. 1 till och med n. 9, den ena seriens alia objectiver med mindre, den 

 andras med storre oppningsvinkel. Jfr. Nasgeli und Schvvendener, 

 Das Mikroskop pag. 630. 



**) Carpenter (The Microscope ed. 3. 1862. pag. 191.) yttrar sig 

 salunda : But it is not the only , nor can I regard it as the chief work of 

 the Microscope, to resolve the markings upon the Diatomaceffi, or tests of 

 the like difficulty ; and although I should consider this as the highest object 

 of ambition to our makers, if the performances of such lenses with test- 

 objects were any fair meausure of their general utility, yet as I think that 

 I have demonstrated that the very conditions of their construction render 

 them inferior in this respect for the purposes of ordinary microscopic 

 research , I would much rather hold — out the reward of high appreciation 

 — to him who should produce the best working microscope, adapted to 

 all ordinary requirements, at the lowest cost. It docs not seem to me an 

 unapt simile, to compare the devotees of large angular apertures to the 

 gentlemen of the "turf." — Schacht (Das Mikroskop 3:te Aufl. 1862, 

 pag. 34) yttrar sig som foljer: "Doch wiirde man sehr irren, wenn man 

 die Giite eines Mikroskopes allein nach seiner Leistungcn fur schiefes Licht, 

 wofiir die Schmetterlingsschuppen und Kieselschalen der Diatomeen zu- 

 meist angewendet werden, beurtheilen wollte. Die Leistungen des In- 

 strumentes oder vielmehr einer bestimmten Objectiv- und Ocularcombination 

 fur gorades Licht sind jedenfalls viel wichtiger ..." — Det ar att marka, 



