466-5 = BOTANICAL GAZETTE [DECEMBER 
the atmospheric oxygen and to the alkalescence of bog waters by aquatic 
plants. Inrare instances the iron deposits may be made up almost entirely of 
the sheaths of the filamentous iron bacteria Gallionella ferruginea and Leptothrix 
ochracea. It may also be possible that deposits in which no bacteria may be 
found may have had their start by the growth of iron bacteria, but later on these 
may have died out and left no trace of their presence. 
_ In regard to the formation of iron rust in water pipes, the author is in accord 
with the observations of the English investigator Brown, and others, who 
believe that very often the incrustations of rust on the inner surface of the pipes 
may begin in areas accidentally left bare in the usual tarring process, and ferric 
oxid is formed by the action of the water entirely apart from the presence of 
iron bacteria, as the author himself has time and again demonstrated. It must 
be remembered, however, that where the presence of iron bacteria can be 
unequivocally established, there must occur the favorable combination of both 
soluble iron and organic food material; lacking the latter in sufficient quantity, 
no iron bacteria can gain a foothold. 
MOoLiscH very timely points out that much of the chalybeate waters bottled 
for medicinal purposes is worthless on account of the precipitation of the iron 
in insoluble form (ferric hydrate). This may be caused in one of two ways: 
(1) by the action of the air acting on the soluble iron carbonate, and (2) by the 
activities of one or other of the iron bacteria. This latter fact is established 
beyond a doubt, inasmuch as ADLER has.cultivated iron bacteria from the 
waters of several chalybeate springs, and by the addition of various antiseptics 
has delayed the action of precipitation of the iron by inhibiting the growth of 
the bacteria. In practice such waters are recommended to be treated by filtra- 
tion or by sterilization by heat. 
The monograph is supplied with a full bibliography of the subject, and is 
plentifully illustrated with colored plates, original drawings, and photographs. 
The work constitutes a most valuable contribution to our knowledge of these 
peculiar and interesting microorganisms.—NORMAN MacL. Harris. 
The morphology of gymnosperms? 
In the present handsome volume the authors have more than doubled the 
size of their book on the same subject published almost a decade ago. It is 
a significant fact that the “fossil gymnosperms,” relegated to an all too brief 
chapter in the earlier edition, are now distributed in accordance with their 
evolutionary sequence, and adequately and even copiously treated. The 
volume begins with the Cycadofilicales, as they are appropriately dubbed, in 
preference to the earlier and less suitable appelations Cycadofilices and 
Pteridospermeae. This group of gymnosperms, which has clearly emerged 
 CouLTER, J. M., and CHAMBERLAIN, C. J., Morphology of gymnospe 
pp. sce figs. 462. Chicago: The University of Chicago Press. 1910. lee 10, 
postpaid 
