522 DESCRIPTION OF [Pot^ffastrica. 



apparatus consists of numerous berry-like stomach-cells, connected 

 together, and presenting a moniliform or necklace-like alimentary 

 canal, which commences at the mouth, and, having made a detour 

 through the body, returns to it. Oscillatoria, Rotatoria, and Monads, 

 are often found abundantly in the stomach-ceUs. The Stentors 

 increase by self-division, either longitudinally or oblique ; and by 

 ova, which form a net-like granular mass, cover the stomach-cells, 

 and vary in colour in different species. There is, besides, a gland-like 

 sexual body, resembling the soft roe of a fish, whose shape is band- 

 like, moniliform, or round. A contractile bladder is also present. 

 The Stentors are among the largest of the Infusoria, and all the 

 species are visible to unassisted vision. They are best examined 

 between the plates of a large live-box, a portion of the decayed stem 

 or leaf on which they are found being put in ■with them. 



"It is in the Stentors (says M. Dujardin), where we can view the 

 several supposed internal organs isolately, that new observations will 

 make Itnown their real nature." 



The Stentors are exclusively found in fi^esh standing water, or 

 between plants where the water is still. They are coloured green, 

 black, or clear blue. 



Stentor MiUleri. — This is the white funnel-like polype discovered 

 by Trembley ; it is large, the crown or wreath of cilia interrupted, and 

 the lateral crest or fringe indistinct. When swimming, the animal- 

 cule is usually contracted in the form of an egg, but when attached, 

 it stretches itself out, like a trumpet, "WTien several are swimming, 

 in a glass vessel, they will gradually congregate, and select some 

 particular spot, and then attach themselves, evincing, as it were, 

 not only a degree of socialty, but (says Ehrenbcrg) a mental activity. 

 These animalcules feed upon coloured food very readily ; the ova 

 are white, the spermatic gland moniliform. "When kept a long time 

 in cylindrical glass vessels they fasten themselves to the sides, form 

 a slimy covering around themselves, and die. Found upon Lemna 

 and other water-plants, even under ice. Size, stretched out, l-20th.; 

 contracted, 1-1 20th. 



S. Roeselii. — In form, size, and crest, this resembles the preceding 

 species, as shewn, elongated, at fig. 233 ; and contracted, as it swims, 

 at fig. 234 ; the latter I'epresentatiou is rather more magnified. The 



