:^0 THE AMERICAN MONTHLY [Jan. 



in its proper place. It can even be "built up" by putting books 

 under it. Botb tlie lantern and microscope rest upon a very 

 thin board which travels with ease on the extension-bed of the 

 camera-box. By this latter simple contrivance, focussing your 

 specimen on the ground-glass of the camera is easily managed. 

 The Optical Axis. — Dr. Sizer explains in the current issue 

 of 7 he Microscope why it is that many have trouble in photo-mic- 

 rography. The optical axes require more attention than usual. 



MICROSCOPICAL MANIPULATION. 



A New Fixing Fluid. — Gustav Mann describes a fluid com- 

 posed of absolute alcohol 100 cc, picric acid to 4 grms. corrosive 

 sublimate 15 grm. Pieces should not exceed 1 cm. in thickness 

 and are left 12-24 hour-s. Then wash in running water and 

 place in 30 per cent alcohol with tincture of iodine sufficient to 

 produce a brown color, for 12 hours, after which the tissue it 

 hardened gradually in alcohol and imbedded in paraffin. 



A shorter method is to wash in absolute alcohol for 10 hours 

 changing the fluid at least once and then, alter sectioning, treat 

 the sections with iodide of potash s )lution. It is stated ihat 

 the plasma and nuclei are well fixed with slight shrinkage and 

 the cell outlines are well brought out. {Anat. Anzeiger, VIII, 

 12-23.) 



A Microscopic Clearer. — Lenz recommends the use of a 

 solution of sodium salicylate for clearing preparations for the 

 microscope. This body has great advantages over chloral, as it 

 very quickly transforms starch granules into a transparent jelly 

 which is not disturbed by the addition of glycerin or water, 

 and still turning blue with iodine. Further, it has less detri- 

 mental effects on the ordinary tissues than chloral. — British and 

 Colonial Druggist. 



BACTERIOLOGY. 



Study of the Organization of Bacteria. — Mitrophanow 

 (International Ztschr.f. Anat. u. Physiologic) examined the large 

 pigmented sulfo-bacteria as chromatium, rhabdochromatium 

 and ophidomonas, as also beggiatoa and allied saprophytes, 

 crenothrix, spirilla, bacilli and bacteria. The living organisms 



