172 DESCRIPTION OF IPoIt/c^astrtca. 



Such obsei'vations tend to render the aniinality, not only of thiii 

 vibrio doubtful, but also of the similar but smaller V. Bacillus a 

 matter of uncertainty. 



Genus SriEOCHOETA. The twisting Animalcules. — This genus is 

 characterized by its members being developed in filiform and flexible 

 chains, of a spiral description, lengthening by the imperfect or in- 

 complete mode of self- division. The details of then' organization 

 are at present unknown to us. Dujardin does not admit this as a 

 genus distinguishable from Spirillum. 



S. plicatilis (V. serpens, M.) Chain constituted of very delicate 

 bodies, of nearly globular shape, connected together in a long filiform 

 spiral, having numerous and closely aiTanged coils; colourless. Group 

 62 shows three clusters. Found at Tilbury Fort. Length of chain 

 l-170th to l-440th. Thickness l-12000th. 



Genus SpiEiLLtrM. The cylinder spiral Animalcules. — This genus is 

 characterized by its members developing themselves in tortuous 

 chains, or inflexible and cylindrical spu-als. These are elongated in 

 the same manner as before described, by the iucomplete self-division 

 of the creatures, which takes place in an oblique direction. Their 

 brisk, energetic, and voluntary motion, and the increase of the chain 

 by division, are the only animal properties which have been hitherto 

 observed as characteri2dng the creatures. 



S. tenue. Spiral consists of three or four coils, constituted of very 

 slender, slightly bent, and colourless fibres ; articulations distinct. 

 Found in vegetable infusions. Length about 1 -900th. Thickness 

 1 -1200th. 



S. undula (V. undula M.) Spiral consists of one and half turns; 

 fibres short, stout, and much bent ; articulations distinct ; colourless ; 

 when dry, the articulations are more distinct. Ehrenberg remarks, 

 that the fonn of this species is like a bow; and Miiller, that it 

 resembles the letter V. Fig. 61 represents a group magnified 800 

 diameters ; the dotted lines indicates the impression left on the 

 eye when the creature is in motion. Found in stagnant water 

 having a mildew scent. Length about 1-1 500th. Thickness 

 l-20,000th. 



S. volutans {Vihrio spirillum, M.) Consists of three, four, or more 

 coils ; fibres verj' tortuous, long, and stoixt ; articulations distinct ; 



