384 Dr. R. Greef on the Structure and 



XXI. — Investigations upon the Structure and Natural History 

 of the Vorticellse. By Dr. Richard Greef. 



[Continued from p. 211.] 



Body-cavity and Digestive Organs of the Vorticellse. 



We are indebted to Ehrenberg for the first correct notion of 

 the nutritive apparatus of the Vorticellte. Whilst, before his 

 time, as has ah-eady been remarked, it was supposed that the 

 body of these animals constituted a hollow bell open anteriorly, 

 he showed that the anterior opening of the bell was closed by 

 a ciliated disk, and that it was only behind this disk that a 

 lateral orifice led into the interior of the body. He likewise 

 correctly determined the position of the anus as an orifice se- 

 parate from the mouth but lying in the same pit, which, as 

 we have already remarked, must be regarded as an essential 

 systematic character of the Vorticellan family. The mouth 

 and anus were said to be united by a curved intestine hanging 

 down to the bottom of the body ; and to this, in accordance 

 with his conception of the polygastric nutritive system of the 

 Infusoria, the stomachal vesicles were supposed to be appended 

 by small lateral cieca. 



After the refutation of the polygastric nutritive system, espe- 

 cially by the striking observation of the constant circulation of 

 the whole contents of the body in Paramecium (Focke), the 

 knowledge of the digestive apparatus of the Vorticellse made 

 an important advance by means of the researches of C. F. J. 

 Lachmann (of whose labours science was unfortunately so 

 early deprived), whose beautiful and careful investigations 

 form to a certain extent a new starting-point in the examina- 

 tion of the entire structure and natural history of these ani- 

 malcules. 



Lachmann showed that the cilia upon the ciliated disk are 

 not placed in circles, as Stein stated, but run in a spiral line 

 to the mouth, which, indeed, Ehrenberg had already distinctly 

 seen, as appears from many figures in his great work on the 

 Infusoria (e. g. Taf. xxv. fig, ii., Taf. xxviii. fig. iii. 3, 2 &c.). 

 But to Lachmann's observations we are indebted for the exact 

 determination of the course of the series of cilia, which com- 

 mences on the right from the external aperture of the nutritive 

 tube, previously called the buccal orifice, runs round the ciliated 

 disk once or several times, and then descends in a curve into 

 the above-mentioned orifice and traverses the first part of the 

 nutritive tube. This commencing portion he called the vesti- 

 hidimi, after the example of Johannes Miiller. The vestibulum 

 consequently forms a part of the ciliary spiral, and cannot well 

 be regarded as the cesophagus or as a part of the food-tube, 



