98 THE OCEAN WORLD. 
appear the most interesting, from their size, structure, rarity, or 
abundance. 
Included among these, but, according to Cohn, apparently be- 
longing to the vegetable kingdom, we find the family of Vibrionide, 
so named from their darting or quivering motion, including the 
eel-like microscopic animalcules which occur in stale paste, vinegar, 
&c., with some others, which are parasitic on living vegetables, 
such as Vibrio tritici, which infests the grains of wheat, producing 
the destructive disease called corn-cockle or purples. They are fili- 
form, extremely slender, without appreciable organisation or apparent 
organs of locomotion. They are among the first organisms which 
show themselves in any infusion of organic matter. By using micro- 
scopes of the highest magnifying power, they present the appear- 
ance of very thin short lines, either straight or sinuous, the thickest 
of them not exceeding the thousandth part of the fraction of an 
inch. They are contractile, and propagate by spontaneous fission, 
often imperfect in character, and hence giving rise to chains of 
greater or less length. Among them some resemble right lines, more 
or less distinctly articulated, and endowed with a very slow move- 
ment, these are Aacteria; others are flexuous and undulating, and 
more or less lively ; these are true Vzdrios; others have the body 
fashioned in the form of a corkscrew, turning unceasingly upon them- 
selves with great rapidity, these are the Sgiri//a, having an oblong 
fusiform or filiform body, which undulates or turns spirally upon 
itself. 
The Bacterium termo (Fig. 29) is one fo the smallest of these 
organisms, and is, according to Cohn, the motile phase of an alga. 
It is found, at the end of a short time, in all vegetable or animal 
infusions exposed to the air. It shows itself in infinite numbers, 
forming perfect swarms, which disappear as other species multiply in 
the liquid, to which it serves for nourishment. When the infusion 
becomes too foetid for these new species to live in it, in consequence 
of fermentation or putrefaction, the Bacterium termo reappears. This 
species was one of the first observed ; Leuwenhoek found it in the 
white matter which is called teeth tartar, and which is met with 
in the teeth and gums. It is also found in the fluids of various 
animals which have been affected by disease. 
The Wand-like Vibrio (Fig. 30) has the body transparent, 
filiform, and long articulations, often appearing as if broken at each 
connection. It moves very slowly in the water. Leuwenhoek 
observed this second species joined to the first in the teeth tartar, 
and also in a great number of organic infusions. 
