558 STUIilAUY OF CURRENT RESEARCUES RELATING TO 



washed in water or 1 per cent, acetic acid, and then in 50 per cent, 

 alcohol, and dried (firstly between folds of blotting-paper, and then 

 by passing them several times through a flame). In this way one 

 can obtain a perfectly satisfactory double-stained specimen in four 

 minutes. 



Staining Bacteria with Dahlia.* — Dr. Eibbert employs for 

 staining the micrococci of pneumonia in sputum a solution' of dahlia, 

 which stains the cocci deej) blue and the capsules of a lighter hue. 

 Typhoid bacilli in lymphatic glands were better stained by a solution 

 of dahlia in anilin water, according to Gram's method, than by any 

 other process. 



Pergens's Picrocannine.t — This is prepared as follows : — Boil 

 for two hours and a half 500 grms. pulverized cochineal in 30 litres 

 of water. Add 50 grms. potassic nitrate, and, after a moment of 

 boiling, GO grms, oxalate of potash ; boil 15 minutes. On cooling, 

 the carmine precipitates ; it is washed several times with distilled 

 water in the course of three or four weeks. Pour a mixtui'c of one 

 volume of ammonia with four volumes of water upon the carmine, 

 taking care that the carmine remains in excess. After two days filter, 

 and leave the filtered solution exposed to the air until a precipitate 

 forms. Filter again, and add a saturated aqueous solution of picric 

 acid ; agitate, and then allow it to stand for twenty-four hours. Filter, 

 and add 1 grm. chloral for each litre of the solution. At the end of 

 eight days separate the liquid from the slight precipitate which is 

 formed, and it is ready for use. 



This liquid keeps unchanged for at least two years, and is recom- 

 mended by Carnoy in preference to other picrocarmine solutions. 



Application of the Colouring Matter of Red Cabbage in His- 

 tology. + — Dr. M. Flesch concentrates the watery extract of red 

 cabbage by evaporation, mixes with a solution of acetate of lead, and 

 precipitates the latter as insoluble carbonate of lead by carbonic acid, 

 w^hereby the greater part of the colouring matter is thrown down 

 with the lead precipitate. After washing on a filter, the precipitate 

 is dissolved by acid, the solution carefully neutralized, and treated 

 with sulphuretted hydrogen. The filtrate contains a clear solution 

 of the colouring matter, which is dried and dissolved, one part in 

 water and another part in alcohol. In fresh preparations nuclei arc 

 stained green and protoplasm red. Both solutions proved to be good 

 nuclear stains, even in preparations (brain hardened in chromic acid) 

 in which carmine failed. 



Double Staining.§ —The following solutions arc recommended by 

 Dr. J. Bruu for animal histology. 



a. Blue. Soluble prussian blue 1 grm., oxalic acid 0-25 cgrm. 



• BB. d. Niederrhein. Gesell. in Bonn, 1884, pp. 2i4-5. 



t Araer. Natural, xix. (1885) p. 428, from Carnoy's 'Biologic Cellulaire,' 

 1884, p 92. See also Lee's ' IMicrotomist's Vade Mecum,' 1885, p. 00-1. 

 + Zeitschr. f. Wiss. Mikr., i. (1884) pp. 253-4. 

 § Arch. Sci. Phys. et Nat., xiii. (1885) pp. 257-60. 



