D. L. MACKINNON 
283 
Reagent employed 
8. Alcohol 
(5°/ 0 to 100%) 
9. Glycerine 
(5 % to 85 %) 
10. Quinine (sulphate) 
(•01 % to 10%) 
11. Soamin (1 %) ... 
Effect on Spirochaeta recurrentis 
much paler. After 18 hours no further change, except that in 
the stronger solutions the spirochaetes often appeared very 
pale and shadow-like. 
Immobilization instant in the stronger solutions—in solutions 
below BO % this was more gradual. No appreciable change in 
form, beyond occasional slight flattening of curves. 
Immobilization complete in about a minute or two in the weaker 
solutions : above 25 % it was almost instantaneous. The form 
was very little altered, except for occasional marked flattening 
of the curves. No further change after 23 hours. (Fig. 2.) 
Instant immobilization. The curves became much flattened out: 
frequently the spirochaetes were almost straight, or minutely 
“crinkled.” This was particularly marked in the stronger 
solutions, but was noticeable in all. (Fig. 3.) 
Much the same effect as in distilled water. A few spirochaetes 
still moving after 10 minutes, but only very sluggishly. No 
alteration after 16 hours. 
12. Arsacetin (5 %)... 
13. Trypanblau (1 %) 
14. Trypanrot (2 %) 
Some immobilized at once: the majority continue to move slug¬ 
gishly for a few minutes. The general appearance was much 
as in distilled water. No alteration after 16 hours. 
Much the same effect as in distilled water. A stronger tendency 
for the spirochaetes to form intertwining bundles: frequently 
the individuals forming the grorrps were much twisted upon 
themselves. 20 hours later, no alteration. (Fig. 4.) 
Same as in (13). 
Conclusions. 
The form of Spirochaeta recurrentis is not appreciably altered by 
immersing it in distilled water, NaCl solutions, alcohol, soamin, arsacetin, 
trypanblau, trypanrot. Flattening of the curves of the spiral produced by 
glycerine, citric acid, formic acid, nitric acid, quinine and hydrochloric acid 
—this effect is most marked in quinine and hydrochloric acid. In several 
of the reagents employed—notably quinine, HC1, trypanrot and trypan¬ 
blau and in distilled water—there is a distinct tendency for the spiro¬ 
chaetes to curl up at their extremities, and to become intertwined in 
bundles. There is no evidence of plasmolysis. The spirochaetes dissolve 
readily in caustic potash : the acids employed tend to make them become 
paler. All the reagents produce rapid immobilization. 
For the sake of comparison with the above, and in order to bring 
together into a convenient form observations scattered throughout the 
literature, I have drawn up a tabular summary of the results of previous 
experiments similar to mine 1 . 
1 The list contains all the chief references, but cannot pretend to be exhaustive. 
