12 



LIFE, IN ITS LOWER FORMS. 



■white mucor, or mouldiness. Such a fragment placed in 

 the "live-box" of the microscope will not fail to present 

 many groups of one of the most attractive of all the 

 Infusoria, the lovely genus Vorticella. (See Plate I. Fig. 1.) 

 A little bell of glassy transparency is affixed by a sort of 

 nipple to a slender filament or stem, eight or ten times its 

 own length. The bell has a broad and thick rim or lip, 

 within which, on the two opposite sides, are apparently two 

 pairs of cilia,* which are sometimes withdrawn, sometimes 

 protruded, and are vibrated with a rapid snatching motion 

 (a). The result of this is very curious, for when any 

 atom in the water is drawn near the bell-mouth, it is not 

 driven away or drawn in, but is whirled round in a con- 

 tinuous circle above either pair. This gyration may be 

 frequently seen, even when the cilia are so far withdrawn 

 as to be invisible. 



Within the glassy bell are seen many pellucid bodies, 

 which have been supposed to be numerous stomachs ; 

 these are continually changing their sizes, forms, and 

 relative positions ; since they are 1 ot defined vesicles, but 

 simply excavations of the common mass of gelatinous 

 flesh, produced by the escape of the food from the open 

 extremity of the gullet. Besides these globules, there are 

 scattered granules, a contractile bladder, and a band-like 

 dark organ, which is called the nucleus, and which appears 

 to possess the reproductive function. 



In general, the animal floats loosely through the water, 

 the thread fully extended, but rarely so straight as not 



* The cilia are really placed in a complete circle around the bell-mouth ; and 

 the appearance above mentioned is merely an optical illusion, dependent on 

 the relation of these parts of the circle to the eye, as viewed in perspective. 



