282 
Action of Chemicals on Spirochaetes 
the reagent was diluted (with citrated salt solution where possible) in 
about six graduated strengths, and these were allowed to diffuse in minute 
quantities below the cover-glass, the effect of each dilution being care¬ 
fully watched on the living organism. Care had to be taken to prevent 
the diffusion currents from being too violent, as these were apt to distort 
the spirochaetes mechanically, and so vitiate the results. 
The following table gives the results of my observations : 
.Reagent employed 
1. Distilled water 
2. Sodium chloride 
(1 % to 40%) 
3. Caustic potash ... 
(5 % to 25 %) 
4. Hydrochloric acid 
( 01 % to 10 %) 
5. Nitric acid 
(2 °/o) 
6. Citric acid 
(•01% to 10%) 
7 
. Formic acid 
(•02 % to 40 %) 
Effect on Spirochaeta recurrentis 
Spirochaetes gradually immobilized—by the end of a few minutes 
all at rest. There was a strong tendency to collect in tangled 
skeins. Occasionally an individual showed flattening of its 
curves. There was marked blurring of outlines. 
Distilled water after 25 % salt solution produced no effect. 
All solutions immobilized (in the stronger solutions, instantly), 
but produced no other effect beyond giving the spirochaetes a 
more refractive appearance. Unchanged after 16 hours. 
Majority of spirochaetes dissolved. Some remained as pale 
shadows. 
All dilutions produced instant immobilization. The spirochaetes 
had their curves much flattened out, or even reduced to minute 
irregular “ crimping ” : there was also a tendency to coil at the 
ends, and they were often twisted together in parallel bunches. 
They became paler, but were not dissolved after 16 hours. 
(Fig- 1-) 
Produced much the same effect as hydrochloric acid. On the 
whole, the spirochaetes seemed less inclined to curl and twist up. 
Spirochaetes at once immobilized: there was a tendency to run 
together in bunches: they also became paler and showed 
occasional flattening of curves. Undissolved after 6 hours. 
Instant immobilization: curves frequently much flattened out: 
occasional tendency for curling over at the ends : many become 
