120 Dr. C. F. J. Lachmann on the Organization of Infusoria. 



some species of Epistylis, &c.) it scarcely describes more than 

 one circuit round the disi, whilst in Opercularia articuluta and 

 Epistylis flavicans it runs round the disk three times*, and in 

 others the length lies between these two extremes. This por- 

 tion consists of a double row of cilia ; those of the outer row are 

 usually somewhat shorter than those of the inner, and inserted 

 upon the cihary disk nearly in the same line, but at a different 

 angle, as they appear to be far more strongly bent outwards f : 

 in the vestibidum and oesophagus the cilia appear to stand in a 

 single row. The peristome bears no cilia : those represented 

 upon it by Stein belong to the outer series of cilia of the disk, 

 or to that portion of the spiral which descends on the stem of 

 the rotatory organ into the vestibulum. The latter also, perhaps 

 in conjunction with the bristle above mentioned, appear to have 

 been what induced Ehrenberg to suppose the existence of a frilled 

 lovA^er lip in Epistylis nutans, and Stein in all the Opercularice. 



To see the particulars above described, it is peculiarly advan- 

 tageous to observe animals which have died during expansion ; 

 the outline of one of these is shown in PL IX. fig. 2. 



By the vortex produced in the water by the cilia of the spiral, 

 the small particles swimming in the vicinity are attracted and at 

 last reach the vestibulum ; a portion of them is constantly thrown 

 out again, and another portion is whirled doAvn into the pharynx 

 through the oesophagus. Besides the cilia of the spiral, some 

 sti-onger cilia {e and/) also stand in the vestibulum in front of the 

 mouth; these do not take part in the regular activity of the others, 

 but only strike forcibly sometimes, apparently to remove from 

 the vestibulum coarse substances which may have got into it, and 

 also the masses of excrement. [These are also figured by Stein 

 in all Vorticellina.'] In the fusiform pharynx {h, i) the nutri- 

 tive matters are aggregated into one morsel, which, when it has 

 attained a certain size, is passed into the interior of the body J. 

 Meyen § calls this fusiform part a stomach, in which I cannot 

 agree with him, as it evidently serves only for the aggregation of 

 the food into morsels, and the digestion only takes place further in 

 the interior of the body ; I have therefore preferred for it the 



* For this reason Stein describes three circles of ciha on the disk of 

 the former. 



t In the Plate the cilia of the outer series are only indicated at the mar- 

 gin of the figures, but omitted in the remainder of the ciliary spiral in order 

 to prevent the figures from appearing too complicated. 



\ Pouchet (Comptes Rendus, Jan. 16, 1849) speaks of a respiratory 

 organ in the Vorticellce, which, from his description, can only be the pha- 

 rynx. The value of his statements regarding the polygastric structure of 

 the Infusoria is sufficiently clear from this, as he considers the commence- 

 ment of the digestive apparatus as not belonging thereto. 



§ Miiller's Archiv, 1839, p. 75. 



