ZOOLOGY AND BOTANY, MICKOSCOPY, ETC. 255 



Should it be desired to stain both tubercle bacilli and elastic fibres 

 the preparation should be stained with the anilin-gentian solution, de- 

 colorised with hydrochloric acid-alcohol, and then stained with Weigen's 

 solution for 20-30 minutes. After this it is again decolorised in hydro- 

 chloric acid-alcohol and then stained with auramin. By this method 

 the tubercle bacilli are blue and the elastic fibres grey-blue, both 

 standing out sharply against the yellow background. 



Picro-carmin Solutions.* — In connection with radula preparations 

 K. Diederichs gives the following list of picro-carmin solutions, all of 

 which are suitable for staining raduhe. 



(1) Eanvier's. A saturated solution of picric acid and a saturated 

 solution of ammoniacal carmin are mixed and evaporated in a water- 

 bath to one-fifth of the previous volume. The carmin precipitate is 

 filtered off when cold. On further evaporation the solid picro-carmin 

 is obtained as a yellowish-red powder, which is dissolved in distilled 

 water and used as a 1 p.c. solution. 



(2) Bizzozero's is made by dissolving 0"5 grin, of carmin in 3 ccm. 

 of ammonia and 50 ccm. of water. To this is added, stirring constantly 

 the while, a solution of 0*5 picric acid in 50 grm. water. The fluid is 

 evaporated to half its bulk (50 ccm.) in a water-bath, and when cold 

 10 ccm. alcohol are added. 



(3) Friedlaender's. To 1 part of ammoniacal carmin, 1 part of am- 

 monia, are gradually added 2-4 parts of a saturated solution of picric 

 acid. The mixture is constantly stirred the while, and the picric acid 

 solution is added until it ceases to be dissolved. After filtration a few 

 drops of phenol for every 100 ccm. are added. Subsequent cloudiness 

 is removed by addition of ammonia. 



(4) Weigert's. 2 grm. carmin and 4 ccm. of ammonia are mixed, 

 and after 24 hours 200 ccm. of cold saturated aqueous picric acid solu- 

 tion are added. After a further 24 hours acetic acid is added until a 

 precipitate forms. Then the solution is treated with ammonia until it 

 becomes clear. . 



(5) Hover's. 1 grm. of carmin is dissolved in 1-2 ccm. of ammonia 

 and G-8 ccm. of water, and then the mixture is heated in a sand-bath 

 until the ammonia is driven off. When cold the solution is filtered, 

 and then 4-6 times its bulk of alcohol are added. The precipitate 

 which forms is filtered off, washed and dried, and then dissolved in a 

 strong solution of neutral pier ate of ammonia. 



(6) Orth's picrolithium-carmin. Lithium-carmin solution 1 part, satu- 

 rated aqueous solution of picric acid 2 parts. 



(7) Blochmann's Lyons-blue borax-carmin. Stain first with borax- 

 carmin and afterwards with aqueous solution of bleu de Lyon with 

 10 p.c. alcohol (96°). When the sections look blue extract with 

 alcohol. 



(8) Orange G alum-carmin. Stain for 24 hours in saturated aqueous 

 solution of orange G, then in Grenadier's alum-carmin for 10 minutes. 

 Wash and treat with alcohol. 



(9) Carmin-hgeniatoxylin (Fritsch). After dissolving carmin in am- 

 monia the latter is evaporated off. When required for use, a small 



* Zeitscbr. angew. Mikr., vii. (1901) pp. 30-3. 



