A New Genus of Thread-Bacteria. 
25 
1906-7.] 
seen that right and left turns are fairly evenly distributed. Again, two 
individuals twining round each other are as common as those that are free. 
When once they have caught on, twisting takes place till the whole course 
has been traversed. Examples are given in figs. 5, 6, 24. In fig. 24 the 
process is shown in the case of two long threads. As is evident in this 
figure, twining round another organism is carried on until the length of 
the shorter is exhausted, after which the remainder of the longer thread 
twines on its own accord. Usually, however, the twining individuals are of 
the same length (figs. 5, 6). At first I thought it somewhat remarkable 
that more than two individuals do not interlock, as the organisms in the 
deposit on the bed of the stream are always massed very closely together, 
and it would appear that one organism would touch several others. It 
seems to me, however, that when they are thickly massed together in the 
deposit, the time of twisting is past, and it is doubtful whether the 
organism, apart from the conidia, is alive. Again, the twisting must be 
accomplished before a thick deposit is laid down, otherwise a very large 
inertia, probably greater than the capacity of the plant, has to be 
overcome. 
Vegetative Division. 
So far as I have observed, vegetative division is entirely absent in this 
species. In fig. 25 is shown a case in which division by a transverse slit 
has apparently taken place, but this was the only case of the kind which I 
have met, and, whilst admitting the probability of this method of multi- 
plication taking place under other conditions, at present the matter must be 
left in doubt. The development of conidia, however, is so prolific and so 
universal, that it is possible that the plant has adopted this method of 
multiplication to the exclusion of the other. 
Conidia Formation. 
The formation of conidia in this species, as in Leptothrix, is very prolific. 
I have also found that Gallionella ferruginea (or Chlamydothrix ferruginea, 
Migula) can also form conidia in quite as prolific a manner as Leptothrix. 
It has been hitherto unknown in Gallionella ferruginea, and I intend 
publishing the investigation shortly. This conidia formation is thus the 
commonest method of multiplication in all the iron-bacteria of this 
neighbourhood, and marks both an advance in development over the other 
bacteria, and is an important connotative mark indicating the close alliance 
of these three forms. The first appearance of the conidia is indicated by 
large dark dots marking the surface of the flat organism (figs. 5, 11). 
These dots are obviously produced by very slight protrusions, and can be 
