341 
1907-8.] Five New Species of Iron -Bacteria. 
to its scarcity in the iron- water samples which I have up to now 
examined. 
4. Spirophyllum tenue (Ellis). — As each individual of this species 
consists of a spirally twisted fiat band, it belongs to the genus Spirophyllum, 
of which only one species, viz., Spirophyllum ferrugineum, has hitherto 
been described. 
I have seen this species in one place only, viz., near Alexandria in 
Benfrewshire. The band is about 1/j. in width. Its general appearance is 
represented in fig. 4. As there may be 200 and more spiral turns, the total 
Fig. 4. — Spirosoma tenue. 
Fig. 5. — Spirosoma solenoide. 
length is considerable, in spite of the fact that the spirals are very close 
together. Each individual consists of a gently undulating, somewhat loose 
solenoidal structure about 200-300^t long. I am not yet in possession of 
further details as to its life-history. There was a very slight deposit of 
iron on its surface,— so small, indeed, that it was scarcely visible when 
examined under the microscope, — but treatment with ammonium sulphide 
and with potassium ferrocyanide established unmistakably the presence of 
the iron. I hope to be able to elucidate its life-history when more material 
for observation is at hand. 
5. Spirosoma solenoide (Ellis). — This species differs from Spirosoma 
ferrugineum in that the windings are very close together, the whole having 
the appearance of a solenoid. In general appearance it bears a close 
resemblance to Spirophyllum tenue , but a closer observation shows that 
the spiral is made up of a thread , and not a fiat band. In spite of the 
close winding, a length of 100^ and more is often attained ; in fact, the 
average individual is very seldom less than 70 fx. As the thread is about \fj, 
in diameter, and the distance between two turns very seldom more than 
1 /jl, an average individual has about fifty windings (fig. 5). 
The threads are always formed in very small numbers, though fairly 
well distributed over the west and middle of Scotland. I have not yet 
obtained any futher details as to its life-history. 
The investigation, of which these are the preliminary results, is being 
carried on with the aid of a grant from the Boyal Society of London, to 
whom my thanks are due. 
