412 THE MICROSCOPE. 



Monads vary in their colours, some are red, green, or 

 yellow, others nearly colourless. In shape they are round 

 or oval (5 and 6, fig. 226), and possessed of immense 

 activity, having one or more cilia devoted to the purpose 

 of locomotion. Monads have "been claimed "by the bota- 

 nist, and accordingly placed among the Volvocinece, confer- 

 void Alga?. Ehrenberg described them as Infusoria. He 

 says : " All true Infusoria — even the smallest monads, are 

 organised animal bodies." 



Vibrio. — Vibriones. — In this family Ehrenberg wrongly 

 includes the well-known eels in paste and vinegar. 



Vibrio spirilla, Trembling animalcules, when motionless 

 are seen as very minute bodies ; but when exerting the 

 powers of locomotion they take a spiral form, like the 

 threads of a fine screw, and by undulations wind them- 

 selves through the water with rapidity. Each apparent 

 hair is a collection of animals bound together by a pliant 

 band ; thus, as they are individually so small, little is 

 known of their structure. Still they form very interesting 

 objects to view; their very minuteness claiming attention, 

 while their activity and motions excite surprise. The 

 species are numerous, as represented in fig. 218. They are 

 almost invariably the first organisms found in decaying 

 acetous and putrefying organic matters. When treated 

 with iodine and then sulphuric acid, their jointed structure 

 is rendered visible to the higest powers of the microscope, 

 but not otherwise. 



Astasi-ea. — Astasia, signifying without a station, in con- 

 tradistinction to those riving in groups, is the term, given 

 to a kind of crimson-coloured animalcule, the 350th of an 

 inch in length, that exist in enormous numbers, and give 

 the waters in which they live the appearance of their 

 bodies. Ehrenberg describes several varieties of them. 



The family Euglence of Dujardin in many particulars 

 corresponds with that of the Astasia of Ehrenberg ; while 

 Mr. Carter would refer Euglence to the vegetable and 

 Astasia; to the animal kingdom. "The power, however, 

 to vary the figure can be no adequate character, for this is 

 partaken by the gonidia of various algae; the tapering, 

 hairlike prolongation, the existence of one, two, or more 

 ciliary filaments, and the red speck, are also the well- 



