1906-7.] 
A New Genus of Thread-Bacteria. 
21 
VI. — On the Discovery of a new Genus of Thread- Bacteria (Spiro- 
phyllum ferrugineum, Ellis). By David Ellis, D.Sc., Ph.D., 
F.R.S.E., Lecturer in Botany and Bacteriology, Glasgow, and West 
of Scotland Technical College, Glasgow. (With a Plate.) 
(MS. received February 23, 1907. Read March 18, 1907.) 
Introduction. 
Throughout Lanarkshire and Renfrewshire many streams and rivulets 
have beds which are deep reddish-brown in colour. This colour is due to 
the deposition of ferric hydroxide, and in some cases the deposition is so 
great that the course of the stream (if a small one) is hindered, and therefore 
it must be periodically cleared. 
The cause of the deposition is well known. The underlying rocks are 
partly composed of bands of iron-stone which contain a very large proportion 
of ferrous carbonate. This iron-stone is subject to denudation, and the 
carbonate in the form of the soluble bicarbonate FeH 2 (C0 3 ) 2 is set free. The 
consequence is that when water oozes out from the surface it contains a 
large quantity of iron. By the time, however, that the surface is reached, 
oxidation and precipitation have taken place, with the result that ferric 
hydroxide is formed, which is deposited on the bed of the stream or rivulet 
into which the water issuing from the earth flows. This deposit is found 
to consist of organisms belonging to the thread-bacteria or Chlamy- 
dobacteriaceae. Four of these, viz., Leptothrix ochracea, Crenothrix 
polyspora, Cladothrix dichotoma, and Gallionella ferruginea, are well 
known. The brownish-red colour is due to the fact that these organisms 
are coated, often to an extent greater than their own diameter, with ferric 
hydroxide, so that the size of each cell is abnormally increased. Hitherto 
no other iron-bacteria have been known. In Lanarkshire and Renfrewshire 
I find Leptothrix ochracea and Gallionella ferruginea to be exceedingly 
common. Usually the former preponderates, though Gallionella is present ; 
sometimes the latter is absent, and, very rarely, a sample may be found in 
which Gallionella is the predominant factor. About a mile from Renfrew, 
water permeated with ferric hydroxide oozes from the earth and runs along 
a ditch until it is emptied into a small stream which flows into the Clyde. 
The grass in the neighbourhood of the ditch is quite red in colour owing to 
the deposit. 
