SPORE-FORMATION IN THE DISPORIC BACTERIA, 583 
ence of a filament—independent of the cytoplasmic alveoli— 
in another Spirillum, which I hope to describe in a subse- 
quent paper. 
In my first account I stated that the filament in B. 
spirogyra became more twisted before division of the cell. 
This is not always the case ; for I have found one or two 
individuals—though these are uncommon—which are dividing 
when the filament is in the form of an almost straight rod, 
(fig. 6). 
Having said so much regarding the morphology of the 
organism, I will pass on to a description of the phenomena 
observed during spore-formation, which begins in the extreme 
posterior part of the host’s rectum, but is not usually completed 
until the feeces have been discharged. 
The first remarkable fact which I observed was that the 
individuals which were forming spores were little more than 
half the size of the ordinary individuals. After making 
measurements, I found that the average length of sporulating 
forms was about 5—6 p, whilst that of ordinary individuals— 
selected at random—was roughly 9—10 yp. ‘I'he reason for 
this was not difficult to discover. It appears that just before 
sporulation an ordinary transverse division of the cell takes 
place. Each daughter-cell then proceeds to form a spore 
without previously growing to the size of the ordinary 
individuals. 
The details of spore-formation are as follows:—A large 
individual divides into two in the ordinary way—the chro- 
matin filament being the first thing to divide (figs. 7, 8, 9). 
The daughter-cells produced by this division separate and 
undergo a certain amount of growth, though they never reach 
the size of the “parent” cell from which they were formed. 
Inside the cell the filament is seen to consist of comparatively 
few turns, and frequently displays a slight knob at one or 
both ends (fig. 10). One end of the filament now begins to 
enlarge—apparently at the expense of the rest of the spiral 
(figs. 11, 12)—so that a large nucleus-like mass is formed at 
one end of the cell (fig. 12). Up to this stage this body— 
