OF THE PEOTOZOA. CTLIATA. 307 



course along an intestine and enter a cell. I also once attentively observed 

 what appeared to be the extremity of the intestinal canal, to ascertain what 

 the fui'ther coui'se of the coloured particles would be. At this time the animal 

 had not filled any of the cells in its inside ; suddenly two lateral cells became 

 filled, although I did not perceive any nutriment pass along the common tube. 

 This clearly points out that the two cells must be in connexion with the com- 

 mon cavity from which they had become filled ; and when, after the animal 

 has fed for a considerable time, we see that similar filled cells are diff'used 

 throughout the body, this phenomenon aff'ords a ground for the supposition 

 that the intestinal cavity is of greater length than we should at first sight 

 imagine." (Wiegmann's Archiv, 1846, translated in A. N. H. 1847, xviii. 

 p. 433.) 



M. Pouchet, of Eouen (Comptes Renclus, xxviii. pp. 82-516), has also 

 adopted Ehrenberg's notion of definite gastric cells, but has been unable to 

 convince himself of the connecting intestine. Mr. Samuelson also (J. M. S. 

 1856, p. 165 ; 1857, p. 104) seems to coincide with this view; but in his se- 

 veral papers on Glaucoma, cited, there occur variations in description, which 

 very much detract from their weight in deciding on any disputed point. 



Lachmann gives the follo^ving details (A. JSf. H. xix. p. 118) : — " The vesti- 

 bulum continues the spiral line formed by the row of ciHa, constituting a bent 

 tube, which contains a portion of this spire of cilia. In accordance with the 

 direction of this spiral, the concavity of the tube is turned towards the right, 

 and its convexity towards the left : on the convex side the lumen of the tube 

 is still more enlarged, especially in the parts placed furthest inwards, where 

 the anus opens. Between the anus and the mouth which leads further in- 

 wards into the oesophagus springs a bent bristle, which is generally long 

 enough to project outwards beyond the peristome. This bristle is stiif, and 

 is only displaced a little to one side occasionally, when balls of excrement, 

 which are too thick to pass between it and the wall of the vestibulum, are 

 thrown out from the anus ; but it immediately returns again to its old ^Josition. 



" From the mouth a short tube, the oesophagus, with a far smaller lumen 

 than the vestibulum, leads to a rather wider fusiform portion, which we wiU 

 call the phaiyn^v.'' 



This selection of terms we consider unfortunate, because it is opposed to 

 their customary usage in comparative anatomy, — the pharjux being always 

 said to be prolonged into the oesophagus, and not the latter into the former. 

 In aU the Ciliata, except the Vorticellina, the canal continuing from the oral 

 apertui^e is not distinguishable into two portions or segments ; and one terra 

 would suffice to designate it throughout. In that class, where a division may 

 possibly be remarked, it would be better to call the upper segment the pharynx 

 or oesophagus, and the lower the alimentary tube ; by so doing, no false con- 

 ceptions could weU arise. However, in quoting from Lachmann's description 

 we must let the words abide with the meaning he has assigned them. 



To continue our extract — " In most Vorticellina (those with a contractile 

 stem, and the species of Epistylis and Trichoclina) the longitudinal axis of 

 the vestibulum and oesophagus runs tolerably parallel to the plane of the ciliary 

 disk, whilst that of the pharynx has rather the direction of the axis of the body. 

 In these, therefore, the axis of the ciliary spiral, which is continued as far as 

 the pharynx, changes its direction at the commencement of the vestibulum : 

 whilst it coincided vdih. the axis of the body outside the vestibulum, it stands 

 almost perpendicular to it within the vestibulum and in the oesophagus. In 

 the very elongated forms of the Ophrydina (Ehr.), which inhabit sheaths 

 (Ophrydium, Vaginicola, Cothurnia), the longitudinal axis of the vestibulum 

 and oesophagus coincides more with that of the body, as also in the genera 



X 2 



