310 



SCIENCE 



[N. S. Vol. XLII. No. 107» 



Godman states that tlie differences are incon- 

 stant, that a complete gradation evidently 

 exists between the extreme types, and that the 

 two forms can not be considered as more than 

 subspecifically distinct. It is undoubtedly the 

 Atlantic subspecies flavirosiris which regularly 

 visits our coasts. According to the American 

 system, Number 88 of the A. O. U. Check-list, 

 3d edition, should evidently stand as Puffinus 

 kuhli flavirosiris Hartert, Yellow-billed or 

 Azorean Shearwater. Gerald H. Thayer 

 MONADNOCK, New Hampshiee, 

 June 21, 1915 



IKON BACTERIA 



It has been known for many years that some 

 of the higher bacteria are concerned in the 

 precipitation of ferric hydroxide from iron- 

 bearing waters. Thus Orenothrix polyspora, 

 which is often abundant in city water pipes 

 where the water contains a small percentage 

 of iron, is held to be responsible for the fre- 

 quent turbidity of the water in such places, 

 due to the separating out of ferric hydroxide, 

 and also for the filling of pipes with ferric 

 hydroxide which sometimes occurs. Certain 

 other forms, like Chlamydothrix ochracea, 

 Spirophyllum ferrugineum and Gallionella 

 ferruginea, have been abundantly encountered 

 in surface iron-bearing waters, where they 

 form thick gelatinous deposits of yellowish- 

 brown scum. 



More recently certain lower bacteria have 

 been described which show the same charac- 

 teristics with regard to the precipitation of 

 ferric hydroxide and which seem to be very 

 abundant in surface waters. 



Different investigators have attempted to 

 explain this phenomenon in different ways. 

 Some, notably Winogradsky and Lieske, be- 

 lieve that there is an oxidation from ferrous 

 to ferric iron and that this furnishes the bac- 

 terial cell with energy. Lieske also claims 

 that, as the iron is usually in solution as fer- 

 rous bicarbonate, the carbon dioxide set free 

 by the oxidation is used by the cell for build- 

 ing up its tissues. Other investigators, like 

 Molisch and EUis, state that the precipitation 

 of ferric hydroxide is a simple chemical phe- 

 nomenon and is not connected with the life 



processes of the cell. They believe that the 

 accumulations of ferric hydroxide upon these 

 organisms or upon their remains is purely me- 

 chanical. At the same time they admit the 

 association of iron bacteria with iron-bearing 

 waters, and realize that ocherous scums in 

 such waters consist largely of bacterial re- 

 mains. 



Most of the investigations on iron bacteria 

 have been made in Eiirope and relatively few 

 investigators have concerned themselves with 

 the problem. At the present time the writer 

 is engaged in a field and laboratory study of 

 these organisms and it is hoped that this work 

 may throw some further light on the peculiar 

 phenomena connected with their activities. 



During the field work it has been found 

 that iron bacteria are present in almost all 

 iron-bearing waters, surface as well as 

 underground. Orenothrix and Spirophyllum 

 have been found in city waters, Spirophyllum 

 and Gallionella have been found in the under- 

 ground workings of mines even to a depth of 

 several hundred feet, while Chlamydothrix 

 and Spirophyllum have been found in surface 

 iron springs and bogs. It seems that the bac- 

 terial flora of different localities varies. In 

 some localities iron-bearing waters have a 

 mixed flora, while in other localities one finds 

 almost pure cultures of one or another of the 

 higher iron bacteria. Thus some iron springs 

 contain big, fluffy masses of Chlamydothrix, 

 while others contain a brownish-yellow deposit 

 consisting almost entirely of Spirophyllum. 

 Some mines contain in their underground 

 workings only Spirophyllum, while others 

 contain mixed cultures. The reason for this 

 difference is not known, but it is possible that 

 the character of the salts in solution influences 

 the bacterial flora. 



Lower bacteria, of the coccus or bacillus 

 forms which precipitate ferric hydroxide, are 

 more difficult to study than the higher iron 

 bacteria, as they can be distinguished only by 

 their physiological activities. In order to de- 

 termine the general distributions of such or- 

 ganisms in nature various iron solutions were 

 inoculated with different types of wat«r and 

 soil and it was found that ferric hydroxide was 



