190 J3ACTERI0L0GY. 



In this metbod the sections are transferred from 

 water into a solution of aniline-water gentian-violet, as 

 prepared by the Koch-Ehrlich formula, but which has 

 been diluted with about one-third its volume of water. 

 In this the sections remain for about ten minutes, i:iref- 

 erably in a warm place, at a temperature of about 40° C. 

 They should never, under any conditions, be boiled. 

 From tliis they are washed alternately in the iodine 

 solution and alcohol, occasionally renewing the stained 

 with clean alcohol, until all color has been extracted 

 from them. They are then brought for one minute into 

 a dilute ^vatcry solution of eosin or safranin, or Bis- 

 marck-brown, again washed for a few seconds in 

 alcohol, and finally for one-fourth minute in absolute 

 alcohol. From this they are transferred to xylol for a 

 half-minute. TJie remaining steps in the process are 

 the same as those given in the general method. In 

 some cases better results are obtained by reversing the 

 steps in the process and staining the bacteria last, for 

 then the repeated decolorizing action of the alcohol on 

 the bacteria is diminished ; thus, place the sections from 

 alcohol into eosin, safranin, or Bismarck-brown for a few 

 minutes, then wash out in 50 per cent, alcohol, then for 

 from three to five minutes in the dilute aniline- water 

 gentian-violet solution, then into the iodine bath ; after 

 three minutes wash out in alcohol, and, finally, for one- 

 fourth minute in absolute alcohol, and then into the 

 xylol, from which they may be mounted. Some of the 

 organisms which may be stained by this method are 

 micrococeus tetragenus, baoillus diphtheria, bacillus an- 

 thraois, and staphylococcus pyogenes aureus. It cannot 

 be successfully employed with the bacillus of typhoid 

 fever, nor with tissues containing micrococcus gonorrhoea}. 



