846 SUMMARY OF CURRENT RESEARCHES RELATING TO 



evaporation takes place too quickly, more stain must be dropped on. 

 The preparation is then decolorized for a few seconds in 25 per cent, 

 sulphuric acid. The acid is washed out with water, and the prejmration 

 after stained witli a weak solution of methylen blue. The time required 

 for the whole manipulation is not more than five minutes. 



Staining Tubercle and Leprosy Bacilli.* — Prof. N. Liibimofif recom- 

 mends the following solution for staining the bacilli of tubercle and 

 leprosy. It is called borofuchsiu, and consists of fuchsin, 0*5 gi*. ; 

 boracic acid, • 5 gr. ; absolute alcohol, 15 cm. ; distilled water, 

 20 cm. It is made by first mixing the boracic acid and water, then 

 adding the spirit, and finally the fuchsin. The latter dissolves gradually 

 on agitation. 



Thus prepared, the staining fluid has a slightly acid reaction, is 

 transparent, clear, and as it does not deteriorate by keejnng, is always 

 ready for use. Cover-glass preparations of jihthisical sinitum are 

 stained in 1-2 minutes. ISulphnric acid in the proportion of 1-5 is used 

 for decolorizing, the cover-glasses are then washed in spirit, and then 

 immersed for 1^ minute in a saturated alcoholic solution of methylen 

 blue. The superfluous stain is washed off with water, and the cover-glass 

 dried. It is advised to examine the preparation in 01. ligni cedri, or in 

 xylol balsam. Sections are treated in exactly the same way, but it is 

 preferable to stain twenty-four hours in the borofuchsin. The author 

 notes that lepra bacilli arc much more easily and rapidly decolorized 

 than tubercle bacilli. 



Alcoliolic Solution of Haematoxylin.t — Dr. G. Cuccati gives the 

 foUowinc formula for making a hematoxylin solution which possesses 

 the advantages of never going bad, and of staining only the chromatic 

 part of the nuclei, the colour being fixed most deeply in the karyokinetic 

 figures. 



Dissolve 25 grm. of pure iodide of potassium in 25 ccni. of distilled 

 water, and pour the mixture into a glass-stoppered bottle containing 

 75 ccra. absolute alcohol, shaking the while repeatedly. 



Then grind together in a mortar 75 cgrm. of haematoxylin crystals 

 and 6 grm. of alum. When these are intimately mixed, add 3 ccm. of 

 the iodide solution. Keeping the mixture well stirred, add little by 

 little the rest of the solution, and then pour into a well-stoppered bottle, 

 and leave for 10-15 days. At the end of this period shake up well 

 a"ain, and in an hour or two afterwards filter and preserve the filtrate 

 very carefully to prevent evaporation and deposit of alum or iodide 

 crystals. 



This solution only stains up to a certain point, consequently the 

 sections may be left in it almost indefinitely. 



Osmic Acid and Gold cMoride Methods.^ — Dr. A. Kolossow says 

 that the penetrating power of osmic acid, which is intrinsically almost 

 nil, may be increased by a mixture of the acid with uranium salts. The 

 author prepares a 0*5 per cent, solution of osmic acid in a 2 to 3 per 

 cent, solution of nitrate or acetate of uranium (the former is the better). 

 Large pieces of an object, for example a frog's tongue cut into two or 

 three pieces, are easily penetrated by this mixture, wherein they may 



* Centralbl. f. Bakteriol. u. Paraaitenk., iii. (1888) pp. 540-3. 



t Zeitschr. f. "NViss. Mikr., v. (1888) pp. 55-6. } Ibid., pp. 50-3. 



