I] MICROSCOPIC EXAMINATION 23 



Then wash them repeatedly in water. Keep them in absolute 

 alcohol and before use allow them to dry, without wiping, by placing 

 them in a vertical position, protected from dust. 



Bacillus of Typhoid Fevek and Vibrio Cholera Asiatics. 

 Carefully suspend one or two loops of an Agar-Agar culture (ten to 

 eighteen hours old) in a watch-glassful of distilled water. 



(a) With a single loopful of this "suspension" prepare a cover-glass 

 film and allow it to dry in the air. 



(b) Fix it by passing it three times through the flame, holding the 

 specimen in the fingers, so as to avoid over-heating. 



(c) Pour a few drops of solution (a) on the film and allow them to 

 act for half an hour.' 



{d) Wash very carefully in a large excess of distilled water, and 

 then in alcohol. 



{e) Now keep it for three to five seconds in solution (,8), 



(/) Without washing, pass quickly through solution (y). 



ig) Wash again in a fresh quantity of solution (/8), moving the 

 specimen about gently and withdrawing it when the solution begins to 

 turn black. 



(k) Wash it thoroughly in several changes of distilled water. 



(i) Dry it carefully between blotting-paper. 



Mount it first in water and examine it with yV ir;. oil immeision, and 

 if the specimen be satisfactory, mount it permanently in xylol balsam. 



If the flagella are not sufficiently stained; float the cover-slip off the 

 slide and begin again at (/). 



Care must be taken to change the nitrate of silver solution as soon as 

 any precipitation shows itself. 



This is an easy and very trustworthy method. 



Mr Mervyn Gordon has succeeded in producing a uniform and 

 perfect dark staining of the flagella of the typhoid bacilli — far more 

 exquisite than I have seen it produced previously, by introducing in 

 the above method the following alterations : 



(c) Solution (a) is allowed to act for one hotir, instead of half an 

 hour. 



(d) The cover-glass is left iox five minutes in alcohol. 

 («) It is kept for two minutes in solution (j8). 



(/) It is drained on blotting-paper, and left for one and a half to two 

 minutes in solution (7). [The last half minute determines the degree of 

 staining.] 



^ At a temperature of 60° C. five minutes is sufficient. 



