SPIROCHATA BALBIANII AND SPIROCHATA ANODONTA. 39 
number of chromatin masses seen to be connected by a lightly 
staining spiral in successfully stained specimens. At other 
times the achromatic thread was not evident. ‘lhe condition 
of the nucleus was that seenin Spirocheetes on asmaller scale, 
for these organisms are minute. Swellengrebel (10) has 
described such a structure for Spirillum giganteum. 
Further, Schaudinn (20a) has also described the condition 
of the nucleus in Bacillus biitschlii, where the nucleus in 
the resting condition consists of free chromidia scattered in 
the protoplasmic network, which chromidia, in preparation for 
spore formation, condense at the poles with a spiral thread of 
chromatin connecting these poles longitudinally, and along 
this spiral thread chromatin dots or chromidia are dis- 
cernible. 
The more marked or obvious. condition of the spiral is, I 
think, probably connected with some period of relatively 
marked activity in the life-history of the organism, while the 
scalariform arrangement of transverse bars or rodlets with 
less evident connections of achromatic substance is, it seems 
to me, typical of the trophic condition of the organism. 
The structural inter-relations of these two forms or condi- 
tions of the nucleus in Spirocheta balbianii apparently 
arise thus. The transverse bars or rodlets are each composed 
of two chromatin masses (or groups of chromidia) which have 
joined along the helix, the chromatin substance of each of 
the constituent chromatin masses being uniformly disposed 
along the rodlet thus formed. In this process the core of the 
achromatic filament is somewhat altered —it is flattened—and 
the chromatin is concentrated in the rods. 
In the case of division—which is usually fission in a longi- 
tudinal plane, that is, along the principal or long axis of the 
organism—the chromatin rodlets become dumb-bell shaped 
by contracting in or constricting across the middle (text-fig. 
9,d.). The chromatin substance flows into and concentrates 
within the heads of the dumb-bells arranged along the peri- 
phery of the body, and then the dumb-bell shaped rodlets 
break across the centre. This condition would result from 
