90 



SCIENCE-GOSSIP. 



[Apml 1, 1865. 



MICEOSGOPy. 



An Economic Condenser. — The outline figures 

 below are given at the request of an amateur- 

 microscopist, and represent a cheap condenser, 

 whicli lie lias constructed for his own use, and now 

 ] ublishes in the hope that it may be useful to others. 

 Having seen his own instrument, with the con- 

 denser, in operation, we were so well satisfied wilh 

 the results, as willingly to accord him space for his 

 explanation. The woodcuts are executed from draw- 

 ings sent to us with the accompanying particulars : — 



Tig. 1. — A, spot-lens, about l-iuch focus. B, acliro- 

 raatic spot-lens, about I5; inch focus, placed at about 

 the same distance as in a Kelner eyepiece, in a tube 

 C, screwed in a flat ring of metal D, which is sup- 

 ported on a flat plate G, secured by a holdfast E, 

 allowing room between for a diaphragm E, to revolve 

 freely on its axis, which is done by a screw passing 

 through a holdfast into the plate G. B. is a tube 

 5 -inch long for caiTying polariscope. 



Fig. 2.— DiAniRAGM. A, for direct light. B, fro 

 (liflicult test-objects. C, dark-ground illuminator. D 

 small aperture, with shutter E, having a small hole 

 in it. The features presented by this condenser arc, 

 —that it is applicable for both liigli and low powers, 



can be used by merely sliding it into a tube under 

 the stage, and never need be removed except for 

 cleaning." He adds, "it would never make any 

 pecuniary difference to me whether this condenser 

 be used or not. All I have done is for the benefit 

 of any amateur microscopist like myself who, 

 wishing for a reasonably-priced condenser, can 

 gratify that wish."— /. Wehsfe7\ 



What will sVth Objective do ? — Par- 

 ticles too small to be discerned by a sixteenth 

 are well seen by a twenty-fifth or fiftieth, and 

 particles too transparent to be observed by the 

 tv/euty-fifth are distinctly demonstrated by the 

 fiftieth, and Dr. Beale suggests that the further 

 careful study, by the aid of these high powers of the 

 development and increase of some of the lowest 

 organisms, and the movements which have been 

 seen to occur in connection with certain forms of 

 living matter will lead to most valuable results 

 bearing upon the much-debated question of vital 

 acilous. Another very great advantage resulting 

 from the use of the highest powers occurs in 

 minute investigations upon delicate structures 

 which occupy difl^erent planes, as is the case in 

 many nervous organs. In studying the distribution 

 of the nerves in some of the peripheral organs of 

 vertebrate animals, very fine fibres can be followed 

 as they lie upon different planes. The most delicate 

 constituent nerve-fibres of the plexus in the summit 

 of the papilla of the frog's tongue can be readily 

 traced by the aid of this power. The finest nerve- 

 fibres thus rendered visible are so thin, that in 

 a drawing they would be represented by fine single 

 lines. Near the summit of the papilla there is a 

 very intricate interlacement of nerve-fibres, which, 

 although scarcely brought out by the twenty-fifth, 

 is very clearly demonstrated by this power. In this 

 object the definition of the fibres, as they ramify in 

 various planes one behind another, is remarkable ; 

 and the flat appearance of the specimen as seen by 

 the twenty-fifth gives place to that of considerable 

 depth of tissue and perspective. The finest nerve- 

 iibres in the cornea and in certain forms of connective 

 tissue are beautifully brought out, and their relation 

 to the delicate processes from the connective-tissue 

 corpuscles more satisfactorily demonstrated than 

 with the twenty-fifth. — The Reader. 



MiCRO-PiiOTOGRAPiis.— At the meeting of the 

 Microscopical Society, March 8th, an interesting 

 collection of dissolving views was exhibited by the 

 kindness of Mr. James How, of Eoster-lanc,by means 

 of slides prepared by Dr. Maddox. The forms of some 

 diatoms when thrown upon the screen measured 

 over twelve feet in diameter ; a section of echinus 

 spine nine feet ; a scale of a hawkmoth seven feet ; 

 and the blood discs of a newt from two to tlircc feet 

 long, every object being as sharp as a painting. 



