882 DK. E. KLEIN, 
On the 30th of the same month, in addition, a few briskly 
moving individuals of Bacterium termo were to be seen, and 
very numerous, bright, highly refractive, non-moving, rod- 
like structures, which appeared to be offsprings of the 
(spherical) Micrococci. 
In April of this year I first noticed that the sediment 
became covered with a thin film of a rosy tint. While the 
intensity of the colour of the latter went on increasing, the 
sides of the sediment, z.e. the surface touching the glass, 
also assumed that colour, the intensity, however, decreasing 
tuwards the depth. 
At present (middle of July) the sides of the sediment 
possess a distinct rosy hue, whereas the film covering its 
(sediment) free surface, i.e. that which is in free contact with 
the fluid, is of a deep pink colour. The interior of the 
sediment has retained its original colour. 
The film is composed entirely of masses of spirillum, chiefly 
forming Zooglea, between which numerous isolated examples 
are seen. The Zoogloea consists chiefly of what is termed 
by Cohn (‘ Beitrage zur Biologie der Pflanzen, Untersu- 
chungen iiber Bacterien,’ p. 181) Sptrillum undula. Amongst 
the isolated examples, some of which present only occa- 
sionally active movement, I find numerous Spirillum tenue, 
and also some whose size gives them a close resemblance to 
what the same author describes and figures (see his fig. 21) 
as Spirillum volutans ; in our case the last named are, how- 
ever, in a resting condition. Also a few examples of Spiri- 
chete plicatilis (see Cohn’s fig. 22) are to be met with. 
I have found ample evidence to maintain that the Spirillum 
tenue is identical with the Spirichete, from which it differs 
only with regard to length, for I have seen all possible inter- 
mediate forms between the two—Spirillum tenue of four to 
six turns, of six to eight turns, such of twelve turns and 
lastly of more than twelve; those that exceeded eight or ten 
turns were folded so as to resemble completely Cohn’s 
Spirichete plicatilis. Occasionally pairs of Spirillum may 
be seen so arranged as to resemble a Mercury’s staff. 
The Zooglaa-masses are made up, as already mentioned, 
of Spirillum undula. The interstitial substance, in which 
the latter are embedded, is perfectly colourless, whereas 
the Spirilla present a rosy coloration, which is more dis- 
tinct in proportion to the thickness and density of the layer 
formed by them. In the isolated examples and in small 
groups of them the colour is hardly perceptible. 
What has been said with regard to the film on the surface 
of the sediment is true also for the sides of this latter, their 
