1912] CURRENT LITERATURE 185 
ing upon exposure to the moist westerly winds. In the more mesophytic region, 
with an annual rainfall of about 250cm., a rain forest formation develops, 
its conspicuous trees being Podocarpus Hallii, Librocedrus Bidwillii, and two 
species of Phyllocladus. 
In the more xerophytic portion of the region, while the precipitation is 
quite considerable, exposure to strong insolation and almost continuous winds 
produces a steppe formation. This is developed upon several sorts of rocky 
substrata, and is characterized by an abundance of shrubby, tussock, and 
cushion plant forms. The succession in some stony river beds has been more 
carefully studied,” and may indicate the interesting results likely to follow 
more detailed investigation of other similar situations. From a pioneer 
association of certain rocky hillsides. The climax association of the river 
beds is a subalpine scrub of the usual type.—Gero. D. FULLE 
Iron bacteria.—A recent contribution by LieskeE" is of importance in that 
it supplements our knoweldge of the iron bacteria that has come to us largely 
through the writings of Motiscu. It also revives interest in WINOGRADSKY’S 
theory of iron assimilation, and illustrates in its comparative results the ever- 
present danger of generalizing from a too narrow inquiry into the field of 
research. 
The author has made an intensive study of one of the numerous species of 
iron bacteria known as Spirophyllum ferrugineum Ellis, enlightening us regard- 
ing its specific cultural and physiological peculiarities. Unlike Leptothrix 
octhracea studied by Mouiscu, this bacterium does not grow in a medium 
containing organic matter; neither in an iron-free medium, nor in a m 
containing iron salts other than ferrous carbonate or bicarbonate, nor salts 
of any of the other metals. 
Of chief physiological importance is the experimental proof that the 
organism can utilize the carbon of CO, introduced into a flask from which 
every other source of carbon can be excluded; the nutrient medium contains 
in solution inorganic salts, iron filings are added, and CO, is furnished to the 
extent of 1 per cent of the air in the flask. Naturally, then, issue is taken 
with Moriscu, who in his recent monograph (Die Eisenbakterien) denies 
the correctness of WrnoGRADSKY’s hypothesis that iron bacteria require iron 
* Cockayne, L., On the peopling by plants of the subalpine river bed of the 
Rakaia. Trans. a nd P Proc. Bot. Soc. Edinburgh 243: 104-125. 191! 
™ LreskE, R., Beitriige zur Kenntnis der Physiologie von Spirephylium ferru- 
gineum Ellis, einem typischen iscaticktietens. Jahrb. Wiss. Bot. 49:91-127. 1911. 
* Reviewed in this journal, 50: 464. 
