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 Vibrionidce, 

 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 Bacteria : others are flexuous and undulating, and 

 more or less lively ; these are true Vibrios ; others have the body 

 fashioned in the fonn of a corkscrew, turning Unceasingly upon them- 

 selves with great rapidity, these are the Spirilla., 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 Oiganic infusions. 



