162 THE AMERICAN MONTHLY [Jun 
These organisms placed in a weak. solution of methy- 
lene blue continue to move about with the same activity 
as before, and the stained specimens can be preserved 
alive until the following day if care be taken not to ex- 
clude oxygen. 
The effect of the stain varies according to the stage of 
development of the bacilli. During the first two or three 
days the living specimens are entirely and uniformly stain- 
ed in biue exactly like dead specimens. 
When the period of sporulation commences, alongside 
of the totally stained bacilli, the presence of bacilli of dif- 
ferent shapes is observed,partially stained and much more 
clearly. In the same specimens are colored rings in jux- 
taposition to uncolored rings, grouped in the most varied 
manner and without any apparent fixed rule. 
The spore-bearing individuals which appear a littleaf- 
ter, give the clue to these selective coloration phenomena, 
which acquire a still greater clearness when the speci- 
mens are larger—as the turns of the spiral are less ser- 
rated, and the spore-bearing bacilli move more slowly in 
zig-zig fashion. One sees, therefore, that the spores, while 
refractive, have, except in rare cases, absorbed the color- 
ing matter and that the filaments which carry them are, 
in general, more feebly colored, some times even uncol- 
ored, and that in those specimens whose spores are local- 
ized at one extremity on a fixed point on the filament, the 
rings which carry the spores are almost always uncolored. 
Success largely depends on the coloring re-agents that 
are used. ‘The finest quality of Ehrlich’s blue and the 
chemically pure methylene blue of Grubler and Hochst in 
very weak solution are recommended, and they should be 
used at the precise moment when the first sporule-bear- 
ing individuals appear. 
- These phenomena are only visible in the living state; 
dead specimens stain so rapidly and uniformly that it is 
extremely difficult to obtain preparations in which the 
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