546 BACTERIOLOGY. 



anilin dyes. The simple stain method (p. 538) can be ap- 

 plied to sections of the fresh tissue in order to differentiate 

 between the two bacilli. The enormous number of the 

 leprosy bacilli and their massing- in the so-called leper 

 cells will assist recognition. 



Eberth Bacillus. 



This organism, like that of glanders, cholera, etc., can- 

 not be demonstrated in tissue by any process of double 

 staining. In such cases the simple stain method must be 

 used. The sections should be stained in LOmer's alkaline 

 methylene blue for some hours, then washed slightly in 

 water and placed in a 10 per cent, solution of tannic acid. 

 The sections remain in this mordant for from 10 to -60 min- 

 utes, after which they are washed in water, dehydrated in 

 alcohol, cleared in origanum, and mounted in balsam. 



Actinomyces. 



The pus from an absc'ess should be received in mercuric 

 chloride where it soon hardens. The material after imbed- 

 ding in paraffin can be cut into sections which should be 

 fixed to cover-glasses. They can be stained by Gram's 

 method or with hematoxylin. 



In the latter case, the section should be floated in a 

 Petri dish in water, to which a drop or two of Delafield's 

 hematoxylin solution has been added. It should remain in 

 this stain for an hour or more. Eventually, it is trans- 

 ferred to a large volume of water where it remains till it 

 shows a clear blue color. The section is then dehydrated 

 in absolute alcohol, cleared in oil of origanum, and mounted 

 in Canada balsam. 



