1910] CURRENT LITERATURE 465 
Wrvocrapsky that considers iron as a definite necessity for the carrying on 
of the vital processes of the bacteria. Moziscu criticizes WINOGRADSKY’S 
work upon the grounds that that investigator did not work with pure cultures, 
and chose a bacterium (Cladothrix dichotoma) which did not actively store up 
iron as does one of the commoner forms (Leptothrix ochracea), so that his chances 
for accurate observation and deduction were sadly impaired. On the other 
hand, Motiscu has worked with these organisms in pure culture, has demon- 
strated that they can grow realy enough onan aoe Ts and a = 
examination of their protoplasm by an be foun 
Further, he has shown that the iron bacteria can make use of manganese, as 
it occurs in water, in a similar way in which they use iron. According to the 
author, the iron in solution in the water is simply deposited in the viscid sheaths 
accumulations of silica in the case of the diatoms, or in the case of the epidermal 
cells of the grasses. When the bacteria use manganese, it is believed that that 
element is laid down in the sheaths in the form of manganese hydroxid, which 
under the action of the oxygen of the air is probably altered to manganic acid 
and finally to manganite. 
The disappearance of the bacteria from waters that have been subjected 
to certain forms of treatment in which the iron is removed, Mo.iscu explains 
in this way. Whether the form of treatment is that of filtration through sand 
or coke, or by chemical methods, great quantities of soluble organic materials 
in combination with hydrogen sulfid, ammonia, or carbonic acid are coin- 
cidentally removed, and this loss of organic srecsctiowsee is wei real element deter- 
mining the vanishing of the bacteria, tter deprivation 
of the food supply, the absence of the iron being a matter of entire indifference. 
In the case of bog waters, the food supply is in the form of humus organic 
matters that are very readily removed by any method that removes iron. 
There exist in nature, Moiscu states, other organisms than bacteria that are 
capable of fixing iron. These organisms are to be found among the algae, 
flagellates, and infusoria. His student ADLER has also demonstrated that some 
of them are able to fix manganese as well as’iron. In all cases the modus 
operandi is quite similar to that of the bacteria. 
Discussing the nature of the formation of deposits of ochre and bog iron, 
the author takes no dogmatic stand, but weighs the evidence in the light of the 
presence or absence of bacteria in material taken from such sources. The 
finding of bacteria in such deposits argues much for them playing at least a 
partial rdle in the formation, although it cannot be overlooked that there must 
be also a chemico-physical precipitation of insoluble iron due to the action of 
