BY W. D. FRANCIS. 81 
material. These filaments are typical bacteria. They 
vary in size in their natural state from under ly to as much 
as 2.54 in diameter. Like the cocci and short. bacilli, 
they can be stained with basic aniline dyes such as methy- 
lene blue, thionin blue, and basic fuchsin, if the excess 
of hydrated ferric oxide is first removed by treatment 
with a series of increasing strengths of dilute hydro- 
ehloric acid. 
Comparison of unstained and stained preparations 
indicates that the primary elements of the bacteria are 
surrounded by a ferruginous sheath which accounts for 
the comparatively large-sized filaments and their visibility 
when unstained. Further investigation is required to 
show the exact number and character of the species repre- 
sented. A greater or less number of the coccoid and short 
bacillary forms may prove to be stages in the development 
or segmentation of the filaments, as similar modifications 
are known to exist in the bacteria. In fact, numbers of 
the ferruginous filaments when stained are seen to be 
segmented into short bacillus-like elements. The long, 
unbranched filaments, which are the most abundant forms, 
probably belong to Leptothrix. Crenothrix also appears 
to be represented, and some apparently branching forms 
present probably consist of species of Cladothrix. Des- 
criptions and figures of these genera are given by Engler 
and Prantl*. An interesting account of bacteria allied 
both chemically and morphologically to those studied 
by the writer is given by Conn.t The conclusions outlined 
there are similar to several of those propounded in this 
paper. 
Dr. T. H. Johnston, in the writer’s presence, performed 
an experiment which showed that the iron present in a 
sample of the ferruginous material was contained in the 
organisms. He filtered the material and washed the residue 
with distilled water. The filtrate and wash water together 
were tested for iron, but that element was found to be 
absent. As the original sample was found by examination 
*** Die naturlichen Pflanzenfamilien, Leipzig, 1900, I., Ia., pp., 35-40. 
+ Argicultural Bacteriology, Philadelphia, 190], pp. 62-64. 
EF 
