Dr. C. F. J. Lachmann on the Organization of Infusoria. 217 



In Elirenberg's families of the Oxijtrichince, Euplotea, and 

 Aspidiscina, as in the preeedingj we also meet with an internally 

 ciliated oesophagus (fig. 10 h), and a curved line open towards 

 the right, composed of strong cilia (fig. 10 b, f) leading to the 

 mouth (tig. 10/). But besides the cilia of the surface of the 

 body, or still more frequently without these, we find peculiar 

 and more powerful organs of motion, the number and arrange- 

 ment of which may serve for the distinction of the species and 

 genera. These consist partly of very thick cilia i)laced in rows, 

 which might be called ciliary bristles {Oxytrichin<2), partly of 

 peculiarly grouped powerful processes, very thick at the base, 

 and serving as feet, which were denominated uncini by Ehren- 

 berg* (in all three families) ; and besides these, the thin seti- 

 form ])rocesses, distinctly articidated at the base, and called 

 styli by Ehrenberg, occur at the posterior extremity of some 

 OxytrichincE and Eicploteaf. The anus in these animals is situ- 

 ated in the posterior part of the ventral surface (fig. 10 e). The 

 internally ciliated CBsophagus, which in the preceding always 

 formed an open tube, is often collapsed in these at its inner ex- 

 tremity, and thus forms a transition to the oesophagus of the 

 following groups. 



Many Infusoria have a completely collapsed oesophagus 

 — which, as forming a tube distinct from the parenchyma of 

 the body, and hanging freely in the alimentary cavity, is per- 

 haps entirely wanting in some species ; at least I have hitherto 

 been unable to detect it in Amphileptus, most species of Trache- 

 lius, Enchelys, Coleps and Trachelocerca, in which it only ap- 

 peared to be a canal through the parenchyma of the body, — and 

 these are generally incapable of forming roundish morsels like 

 the species hitherto under consideration ; but they usually 

 swallow larger particles, which then pass separately into the 

 cavity of the body, often even without being accompanied by 

 water. It is very difficult to determine whether the oesophagus 

 of these animals is furnished internally with cilia. In some, 

 such as Coleps, this almost appears to be the case ; these swim 

 to any slimy mass, such as a deliquescent Infusorium, press the 

 anterior extremity of the body against it, and open the mouth 

 and oesophagus, which are usually closed, so as to form a wide 

 canal ; the mass lying before the Coleps then passes through 



* Of these, the anterior serve for the actual creeping or climbing; the 

 posterior ones might be suitably denominated trailing feet, as they are 

 generally trailed along behind the animal, and only employed occasionally 

 in giving a subsequent push : these are cleft at the end in some species, as, 

 for example, in Euplotes patella. 



t That one of these styles, in Euplotes patella, bears setiform branches, 

 has been akeady observed. 



