234 Ellis. — The Life-history of Bad Hits hirtus. 
motile, and I think it not improbable that this distinction between Badllus 
and Psendomo 7 ias will, on further investigation, also prove to be non- 
existent. Against this probability may be set the fact that all spiral forms 
of Bacteria are undoubtedly polar in their ciliation, and I have satisfied 
myself in the case of Spirillum volutans ( Spirillum giganteuml!) that 
increased motility on cultivation does not make its ciliation other than 
polar. It must, however, be remembered that in this genus, the body of 
the cell continually undulates when it moves, and is not stiff as stated by 
Migula ( 11 , p. 47), so that this may render the formation of cilia at any place 
other than the poles impracticable. I may say that, in this investigation, 
I have taken every precaution to ensure that the form I have investigated 
was that discovered by Henrici ( 7 ) and named by him Bacterium hirtum. 
The Spores. 
The method of examination was as follows. The material was placed 
in a drop of water, mounted on a coverslip as a very thin layer, and after it 
had dried, passed through the flame somewhat rapidly in order to fix the 
spores on to the glass. At the same time, by comparison with unfixed 
spores mounted in water, care was taken that the size was not materially 
altered by this process. The dried material was then subjected to the 
action of stains. In order to ascertain the size of the spores, treatment 
with stains is necessary, as otherwise the exine cannot be determined with 
certainty. It is seen at once that the spores are somewhat larger than the 
average. As the size of the spores of any particular species varies within 
comparatively narrow limits this should be taken into account in the 
diagnosis of a species. For Bacillus hirtus , the length varies from 1-5 /x to 
2*5 /x, and the breadth from i-o /x to i-8 /jl . 
The size of the spores as compared with that of other species can be 
seen from the following table, taken from the accurate investigations of 
Gotheil (6). 
Length. 
Breadth. 
Bacillus ruminatus 
o-8-i -o j u, 
tumescens . . 
• 2 \ 5 - 3 -°F 
I -7-2-0 j(X 
35 
graveolens 
1 * 39 - 1*7 /x 
3 > 
Petasites . . 
=L 
e* 
c* 
1 
H 
0-83-1-11 /X 
53 
ellenbachensis 
. I *7— 2*2 fJL 
0-833* 
33 
mycoides . . 
. I *4-2* 2 fi 
0-83 /* 
33 
subtilis . 
. I- 7 -I -9 P 
0-83-0-94 f* 
.33 
pumilis . . . 
- 0-94-1-52 p 
o- 553 * 
33 
simplex . . . 
. 1 - 39 - 1-7 m 
0-833* 
33 
cohaerens . . 
. 1 .7-2-2 /X 
0-83-1 /X 
33 
carotarum . 
. 1-31-2-2 JU, 
I /X 
33 
fusiformis 
diameter, 
1.3-1-83* 
