OF THE VOKTICELLINA. 579 



FAMILY III.— VORTICELLINA. (Part I., p. 277 et seq.) 

 (Plates XXYII., XXIX., XXX.) 



Polygastrica with an alimentary canal, the extremities of which are distinct, 

 though they approximate in consequence of its curvature (Anopisthia). They 

 have no lorica. A few are solitary ; but the majority are congregated on 

 pedicles, which often assume elegant ramose forms, like little trees, an ani- 

 malcule surmounting and terminating each branch or pedicle. These arbo- 

 rescent clusters are the result of imperfect self-division. 



The animal organization of this family is very distinct. The entire sui'- 

 face of Stentor is covered with vibratile ciha ; but in other genera they are 

 mostly disposed in the form of a wreath around the head. In some genera, 

 as in Vorticella, Carchesium, and Opercularia, longitudinal and transverse 

 muscles are seen ; the mouth and discharging opening, both lying in the 

 same lateral cavity, have been demonstrated in all. Self- division takes 

 place in all the genera, but is least frequently observed in Zootliamnium : 

 when it is imperfect, not affecting the pedicle, it gives rise to branching 

 forms. Gemmation is also frequent in most genera. Prom theii' great irrita- 

 bility when approached, may be presumed the existence of a system of sensa- 

 tion. Colouring matter is received by all the species ; eye-specks are wanting. 



This family affords (in form indeed rather than in structural homologies) a 

 connecting link between the Ciliata (Polygastrica) and Rotatoria. 



The following curious particulars are appended by Ehrenberg, who re- 

 garded them as indicative of an act of transformation : — 



" The Vorticella developes a pedicle ; divides (casts its exuvia) ; developes 

 posterior cilia ; loosens itself from the pedicle, rambles about ; draws in 

 (after shedding a second exmia) the posterior cilia, sheds them, and &mly 

 attaches itself, preparatory to putting forth another stalk. This cycle of 

 phaenomena is repeated again and agam, and possesses high physiological 

 interest ; it is a retui^ning circle of transformations — a retium to an early 

 condition, similar to that of a butterfly, if it suddenly lost its wings and an- 

 tennae, and again became a caterpillar, in order once more to return to the 

 state of pupa and buttei-fly — or to that of an old man becoming a child, in 

 order to run again his course of life anew." (See Part I. p. 277 et seq., and 

 p. 586.) 



The Yorticellina live for the most part in sweet water, fresh or marine, 

 attached to plants or shells, to Crustacea, to the larvae of insects, (fee. There 

 are, however, a few Vorticellce and ^cyphidece produced in infusions, and even 

 in fetid ones. 



This account of the organization of Yorticellina from Ehrenberg requires 

 considerable alterations and corrections from the present state of our know- 

 ledge of these beings. In Part I. (p. 277), their organization has been largely 

 considered ; yet a few notes here may not be misplaced Any definition of the 

 characters of the group of genera comprehended in this family by Ehrenberg 

 would be imsatisfactory, inasmuch as some forms are included which have 

 no sufficient affinity. Ehrenberg represents the Yorticellina as ha\dng a 

 polygastric alimentary canal so curved that its two ends are conterminous. 

 Now the supposed stomachs, as displayed by using coloured food, were merely 

 vacuoles ; and no continuous alimentary canal penetrates the interior, as sup- 

 posed, but only a digestive tube or oesophagus of variable length, terminating 

 abruptly in the interior by an open mouth. The ciliary apparatus of the true 

 Yorticellina is more complex than appeared to Ehrenberg, — the head of the 

 animalcules being terminated by a peristom or free edge, oftentimes thickened 

 and everted, bevond which a ciliated disc supported on a very retractile and 



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