OF THE HUMAN SUBJECT. 81 



source of danger to others, his isolation may be maintained so 

 long as the bacilli persist. 



Formulae of the stains referred to in this volume : 



Carlol fuchsin (Neelsen's solution'): 



Fuchsin 1 gram 



Absolute Alcohol 



Aqueous solution of Carbolic 



10 cubic centimeters (c.c.) 



Aqueous solution of methylene Hue: 



ylene Blue 2 



lute Alcohol 15 c.c. 



Acid (5 per cent.) 100 c.c 



Methylene Blue 2 grams | Distilled Water 85 c.c. 



Absolu 



Loffler's methylene blue : 

 Concentrated alcoholic solu- 



tion of Methylene Blue 



30 c.c. 



Solution of Caustic Potash in 

 distilled water (1 in 10,000) 

 100 c.c. 



Aqueous solution of gentian violet : 

 Gentian Violet 2.25 gram | Distilled Water -100 c.c. 



Or the following may be used, except for the coloration of 

 the hanging drop (see p. 28). 



Gentian Violet 1 gram I Distilled Water 80 c.c. 



Absolute Alcohol 20 c.c. | 



As gentian violet is a basic dye, the washing of cover-glasses 

 after staining with an aqueous solution of this re-agent is best 

 carried out in tap water, which is naturally slightly alkaline; 

 distilled water extracts more of the dye, and acidulated water 

 yet more. Better than tap water, however, is a solution of caus- 

 tic potash in distilled water, one in 10,000, the use of which for 

 this purpose was devised by Mr. Arthur Mead. The cover- 

 glasses, after staining, are passed through two saucers of the 

 potash solution, and finally through tap water. 



