The Flagella of Bacterium termo. By W. H. Ballinger. 171 
group, and that in some cases they have two flagella at one end, a 
fact which I have frequently confirmed. But there is an immense 
difierence between all the other forms and B. termo, in size. It 
may be helpful to realize what this difference is : and I have given 
copies of drawings from nature of all that Warming and others 
give as possessing motile filaments, which I have been able to 
confirm. They are each magnified as indicated, either to the same 
extent as B. termo, or to two-thirds or a half that extent. Bacillus 
ulna and Bact. lineola (Figs. 5 and 6) I have not hitherto seen as 
included in the list of those possessing flagella ; but they are given 
as drawn by camera lucida from nature during my investigations 
for this paper. Their flagella are certainly not more difiicult to 
demonstrate than the flagellum of the uniflagellate monad whose 
history was studied and described by Dr. Drysdale and myself in 
January 1874.'* A comparison then of Figs. 2, 3, 4, 5, and 6 with 
Fig. 1 will indicate as accurately as may be the relative sizes of the 
varieties now known to be possessed of flagella, when compared with 
B. termo. 
But a still more instructive instance is before me. Dr. Koch, 
in a paper recently published f has given illustrations taken by 
micro-photography, of what he considers to be Bacillus suhtilis (or 
a variety), in which the flagella are distinctly visible in the print. 
I send these photographs, which can doubtless be reproduced by 
lithography. In Fig. 7, Plate IX., the magnifying power is 500 
diameters, and the flagella are distinctly visible. In Fig. 8 the mag- 
nification is 700 diameters, and the form shown at a displays what 
are doubtless its flagella, although they are but feebly and faintly 
manifest. These photographs were, however, not taken while the 
organisms were living, nor in their natural fluid. They were, indeed, 
specially prepared, by drying, staining, and mounting in glycerine ; 
and then photographed. This must to a certain extent superinduce 
change of condition, and even alteration of form. This is manifest 
in the relative thickness of the flagella and the bodies of the forms 
photographed, which is certainly not in all cases as it presents 
itself in the living organism ; this is specially seen in Fig. 7. But 
the wonder is that they are so successfully, and even beautifully 
done. In Fig. 9 I give a drawing from nature of B. suhtilis 
magnified 40U0 diameters, to show at once, the relation of this 
form as a “ species ” to B. termo, and to show the condition in 
which those must have been which Dr. Koch photographed; 
namely, the separated segments, such as a,h, which become pro- 
vided, like B. termo, with flagella, as they divide. 
* ‘ M. M. J.,’ vol. xi. p. 69. 
t ‘Verfahren zur Untersuchung, zum conserviren und Photographiren der 
Bacterieu,’ Von Dr. Koch. Beitrage zur Biologie der Pflanzen. Edited by 
Dr. F. Cohn. Third part, 1877. 
o 2 
