SPORE-FORMATION IN THE DISPORIC BACTERIA. 591 
(pl. 3, figs. 36—39, etc). In such organisms—which are 
obviously two still-attached individuals—the terminal posi- 
tion of the spores is remarkable when considered in relation 
to the disporic forms. Just as the latter have failed to form 
a complete septum, so have the former failed to separate 
after forming the septum. 
The significance of the spiral configuration of the 
chromatin at a certain point in spore-formation in B. 
bitschlii and B. flexilis (text-fig. B, a 3, 4) still 
remains obscure. That it is connected with ‘ conjugation ” 
can scarcely be maintained, however, for as we have 
seen, it is permanently present in B. spirogyra. Perhaps 
a study of spore-formation in other forms may serve to throw 
some light upon its meaning. It may be noted, moreover, 
that Mencl (1905) has found similar arrangements of the 
chromation at certain periods in the life-history of some of 
the remarkable filamentous forms which he studied. 
It seems to me that the parallel between the method of 
spore-formation in B. spirogyra and that of B. butschlii 
is too close to be merely accidental. We have seen that the 
abnormal forms of the one are the same as the normal forms 
of the other. And when we consider further that in another 
case (B. lunula) spore-formation proceeds sometimes as in 
B. spirogyra, sometimes as in B. biitsch11i, then it appears 
to me certain that the process of sporulation is really essen- 
tially the same in all these forms. If this is so, then there 
is but one alternative to my interpretation given above. It 
is, that conjugation takes place in all these forms, but that 
in B. spirogyra (always) and in B. lunula (sometimes) the 
conjugants separate before forming spores. As I have already 
said, there is absolutely no justification for such an assump- 
tion. The nuclear filament undergoes no changes which 
could be so interpreted—either in B. spirogyra or B. 
lunula. The significance of the “conjugation” of B. 
bitschlii and B. spirogyra is, to me, now quite clear: the 
last transverse division in the life-history has, for some 
reason, become abortive—division begins, progresses for a 
