404 BACTERIOLOGY. 
be seen at the ends of the rods, which stain more in- 
tensely, and either at the extremities or along the body 
“¢ vacuoles ’’ are observed, which remain unstained; but 
as these show even less resistant power than the homo- 
geneous bacilli found in other cultures, they are cer- 
tainly not spores, but probably are evidences only of 
retrograde changes and effects of the drying prepara- 
tory to staining. 
Fig. 51. 
Flagella, heavily stained, attached to bacilli. 
The bacilli, when existing under favorable conditions, 
are, although in various cultures to a different degree, 
very actively motile, the smaller ones having often an 
undulating motion, while the larger rods dart about 
rapidly, with a snake-like movement. This movement 
is produced by a number of delicate locomotive organs 
in the form of fine, hair-like flagella, which are arranged 
around the bodies of the bacilli. (Fig. 10, page 48, 
and Fig. 51.) The flagella are usually from eighteen 
to twenty in number, but many short rods have but a 
single terminal flagellum. They are not seen in un- 
stained preparations, nor are they rendered visible by 
