4320 BIOLOGICAL STUDY OF TAP WATER. 
‘ 
There are Leptothrix forms besides the ordinary Cladothrix 
filaments, which, by the breaking up of the threads, produce micro- 
cocci and rod-like forms. The cocci are circular in outline, and have: 
a diameter equalling, or at most double, that of Micrococcus pro- 
digiosus, Cohn. In from 24 to 48 hours these micrococci develope 
into rod-like forms (Bacterium, Bacillus), which again give rise to 
Leptothrix, and by branching to Cladothrix filaments. These 
filaments are often rolled into a loose spiral, and these spirals give 
rise to Vibrios, Spirillum—and Spirochaete—forms. All the forms 
already mentioned may pass into a zooglaea or resting stage. 
Beggiatoa alba goes through pretty much the same modifications. 
There are Leptothrix-like filaments of considerably larger size than 
those of Cladothrix dichotoma, Bacillus, Bacterium, and Micrococeus 
forms. Spiral forms are also developed, which however I have never 
seen in any of the sediment L examined, all the spiral forms noticed. 
having been referred to Cladothrix. 
In the study of these organisms it will be found of great advantage 
to stain them first with rose-aniline, or iodine. 
Before proceeding to enumerate the species belonging to the 
Animal Kingdom, a form must be described which I am puzzled to: 
know where to locate. I have only noticed it occasionally ; and L 
am inclined to regard it as a Desmid. 
The body is spheroidal, in optical section broadly oval, surrounded 
by a firm cytioderm ; color, bright green ; chlorophyll, disposed in 
two lenticular masses ; vacuoles, four ; body surrounded by 7—9 (1) 
stiff, colorless, more or less curved bristles (setae), coming off radially, 
and 3—d times the long diameter of the body in length. Three 
individuals gave the following measurements i 
Diam. (1). 0°0093 mm. by 0.0124 mm. 
(2). 0°01142 mm. by 0°01428 mm. 
(3). O-O121 mm. by 0:0154 mm. 
Habitat, Lake Ontario. Fig. 4. 
Wood describes a globular form of Scenedesmus with radiating 
bristles, to which the organism above described is possibly allied. 
In addition to the foregoing species the vegetable kingdom is 
represented by starch grains, spores of fungi, and occasionally some 
remains of the higher plants, such as pollen grains, cuticle of 
aquatic plants, woody fibre, &e. 
