1891.] MICROSCOPICAL .JOURNAL. 211 



tion of a few ccm. of saturated lithium carbonate solution. It is advised 

 tooverstain the preparation with this solution, and to decolorize with 

 hydrochloric acid-alcohol. The sections are then placed in tap water 

 until they become blue. Any contrast dye may be used afterwards. 



Alum-borax-carmine with acetic acid-ahim. This gives similar but 

 better results than alum-carmine. It is prepared by rubbing up i grm. 

 carmine with i grm. borax and 2 grms. ammonia-alum, and then boil- 

 ing this with 100 ccm. of lig. aluminis acetici for half an hour or 

 longer. It is then decantered, and after 24 hours filtered. 



Ammonia-lithium-carmine with ammonium chloratum. This gives 

 a fine, deep strawberry red color in 1-3 minutes Overstained sec- 

 tions may be differentiated with hydrochloric acid-alcohol. Afterwards 

 they are placed at once in absolute (picric) alcohol. It is prepared by 

 rubbing together i grm. carmine with 2 grms. ammonium chlorate, 

 and boiling in too ccm. water. When cold, to the solution are added 

 drop by drop 15-20 ccm. lig. ammonii caustici and lithium carbonicuin 

 from 0.3 to 0.5. Filter. The solution is ready for use at once, and is 

 very permanent. 



Fixation of the Stain in Methylen-blue Preparations. — Prot. 

 A. S. Dogiel finds that the addition of osmic acid to the picrate of am- 

 monium solution used for fixing methylen-blue is attended with several 

 advantages, not the least of these being that it hardens the tissue just a 

 little, and, secondly, that it stains the medullary sheath of nerves black. 

 The solution is made by adding i or 2 ccm. of a i per cent, osmic acid 

 solution to 100 ccm. of a saturated aqueous solution of ammonium 

 picrate. The stain is fixed by immersing the preparation for 18-24 

 hours in the mixture. It is then transferred to glycerin, diluted with 

 water, in which the color of the nerves wiH keep for quite a long time. 

 Should it be necessary to impart a consistence to the object so that it 

 may be sectioned, the author uses a greater quantity of osmic acid 

 (25-30 ccm. ammonium picrate solution ; 1-2 ccm. i per cent, osmic 

 acid). In this solution the object remains for 24 hours, after which Tt 

 may be imbedded, £?. ^., in elder-pith, liver, etc., and sectioned. — 

 Zcitschr. f. Wiss. Mikr., i8gi. 



Artificial Preparatioxi of the Sphaeroliths of Uric Acid Salts. — 

 Herren W. Ebstein and A. Nicolaier say that if some uric acid be tlis- 

 solved on a microscope-slide in a dilute alkaline solution and watched 

 with the microscope, there is, after slight concentration, a formation of 

 round particles of urates varying in diameter from 2-100 //. These are 

 mixed with needes, either singly or in bundles. As solvents, sodium 

 hydroxide, potassium hydroxide, lithium carbonate, borax, ammonia, 

 and piperazine were used ; the best results were obbiined by using the 

 uric-acid sediment from human urine. 



With the polarizing micioscope between crossed nicols the sphaero- 

 liths showed a right angled black interference cross, the arms of which 

 lay parallel to the polarization planes of the nicols, and, concentric 

 with the middle point of this cross, colored interference rings were 

 seen . 



Similar sphaeroliths were obtained with sodium hydrogen carbonate, 

 so that they may consist either of acid or normal urates. 



The interest of such an observation, as bearing on the formation of 

 urinary calculi, is pointed out. — V'ircho'i.'^s Archiv. 



