DEMONSTRATION OF CAPSULES. 31 
(6) Prepare solution B as follows : 
Gallic acid, 5 gm. ; 
Tannic acid, Bon oe 
Fused acetate of sodium or ‘* 
potassium, Io ‘ 
Distilled water, 350 Cc. 
(c) Prepare films as before. 
(d) Place in solution A for one-half hour ; or, if 
the solution is warmed to 60° C., five minutes are 
sufficient. 
(e) Wash thoroughly in water, then in alcohol, 
then again in water. 
(f) Place for two minutes in solution of nitrate 
of silver (0.25-0.5 per cent.). 
(g) Without washing, place in solution B for 
one and one-half to two minutes, using fresh solu- 
tion for each preparation. 
(A) Wash thoroughly in water, and examine in 
water. If the flagella are not sufficiently stained, 
begin again at (/). 
Always change the silver nitrate solution as soon 
as any precipitate appears. 
IV. Demonstration of Capsules. 
In certain forms the envelopes surrounding the 
cells can be stained as follows : 
1. Welch’s Method.' 
(a) Prepare films without using water. 
(4) Place in glacial acetic acid for a few seconds. 
(c) Remove the acid with filter-paper. 
1 Bulletin of the Johns Hopkins Hospital, p. 128, Decem- 
ber, 1892. 
