SPORE-FORMATION IN THE DISPORIC BACTERIA. 589d 
this is the normal condition, because on the few occasions on 
which I was fortunate enough to find these organisms, they 
were all beginning to sporulate. Hence, it is possible that 
the spiral arrangement of the chromatin appears only before 
spores are formed. I found very few individuals like that 
shown in fig. 20. Most of them had reached a more advanced 
stage in development. 
The first stage in sporulation appears to be the constriction 
into two of a large form (fig. 21). The spiral is much more 
distinct at this stage. In some cases this constriction is so 
complete that two daughter-cells are formed, and separate as 
in B. spirogyra. Hach daughter-cell, in a similar manner, 
then gives rise to a single spore (figs. 27, 28, 29). But in 
about an equal number of cases the constriction was incom- 
plete or subsequently disappeared, and the large individual 
formed two terminal spores (figs. 22, 25, 25, 26), as in B. 
flexilis. The individuals which sporulate by the first 
method are therefore only about half the size of those which 
do so by the second method—these containing two spores, 
those one (cf. figs. 27 and 23). In the large individuals a 
trace of the original constriction was often to be seen (figs. 
23, 26), and once or twice I saw forms in which it was still 
very pronounced (fig. 24). 
Spore-formation appeared to take place just as in B. 
flexilis and B. spirogyra—that is to say, by an aggrega- 
tion of chromatic material to form a spore-rudiment, and the 
subsequent formation of a spore membrane round this. 
When the spore-rudiments are formed they resemble nuclei, 
and the organisms bear a very strong resemblance to a form 
recently described by Swellengrebel (1907 a) as Bacterium 
binucleatum. This bacterium contains two deeply-staining 
bodies, which careful micro-chemical tests lead Swellengrebe! 
to suppose are nuclei. They appear to be constantly present, 
and divide in a curious manner. Another point of resem- 
blance to B. lunula is the curved form which these organisms 
possess, thus causing them to resemble large Vibrios. 
