378 SCIENCE PROGRESS 



to a tenth of the width. The youngest specimens that were 

 observed consisted of very thin half-twisted bands measuring 

 i fi in width and from 4/j, to 6 p in length. These exhibited 

 an independent movement, partly of a trembling and partly of 

 a pendulum nature. The deposition of ferric hydroxide, how- 

 ever, seems to effect an early stoppage of this movement. The 

 fully grown specimens (see central figure in Plate III) may show 

 thirty to fifty twists, and are correspondingly wider and thicker. 

 Except in the very youngest individuals the colour of the 

 bands is rusty red and assumes a deeper tint with increasing 

 age. Since the discovery of this organism its presence has 

 been observed in various parts of Great Britain and lately in 

 America also. On the Continent its presence has not so far 

 been recorded, though there can be little doubt that a search 

 there for it would be attended with successful results. 



Inter-Relationships of Leptothrix, Gallionella, and Spirophyllam 



An intimate study of these three organisms engenders the 

 thought that perhaps they are more closely connected than 

 appears on the surface. With regard to Spirophyllum, Molisch 

 maintains that it is identical with Gallionella. This view, 

 however, is based on the superficial resemblance which un- 

 doubtedly exists between old iron-laden bands of Spirophyllum 

 and similar threads of Gallionella. An accidental resemblance 

 between the " corpses " of these two organisms cannot, however, 

 weigh against the fact that during life from their earliest 

 beginnings the band-shaped structure of the one and the 

 thread form of the other are respectively the distinctive 

 features of the two organisms. Molisch apparently presumes 

 that Spirophyllum is identical with dead Gallionella threads, 

 the spaces between the coils of which have become filled with 

 ferric hydroxide, thus converting the coiled threads of this 

 organism into a band-shaped structure. We must look deeper 

 for an insight into the relationships of these forms. It is note- 

 worthy that Gallionella is never encountered except in the 

 presence of Leptothrix. The same is very nearly true of 

 Spirophyllum. In fact their association is too close not to 

 suggest a very close relationship. Add to this that in their 

 methods of reproduction, in their powers of attracting iron, 

 and in every other respect, except in the shape they assume, 

 these three organisms are identical. Some biologists, like 



