THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[FOURTH SERIES.] 

 No. 50. FEBEUARY 1872. 



XII. — Investigations upon the Structure and Natural History 

 of the Vorticellte. Bj Dr. Eichard Greef*. 



[Plates XII.-XVI.] 



The Vorticellce are among those Infusoria which were earliest 

 and have been most frequently examined. From Leeuwen- 

 hoek, who first observed them and with them the first Infu- 

 sorial forms, down to the most recent times, most naturalists 

 seem to have turned with particular preference to this elegant 

 group of animals. Leaving out of consideration that many- 

 were probably induced, by the exceedingly attractive pheno- 

 mena of form and existence presented by the bell-animalcules, 

 to a closer examination of them, there is perhaps no Infusorial 

 family which can be observed with more ease and certainty. 

 In all waters, whether stagnant or flowing, fresh or salt, Vor- 

 ticelloi occur, often appearing in great quantities by the exten- 

 sion of their colonies. Almost all are attached to stems, and 

 therefore are on the whole better adapted for examination 

 (although with occasional interruptions, as in the contractile- 

 stalked forms) than most other Infusoria, which pass restlessly 

 to and fro in the field of vision, and can often only be brought 

 to the desired state of quietness by a pressure which more or 

 less alters the normal conditions of form and life. 



It is no wonder, then, that, with regard to these animalcules, 

 many interesting facts of extreme importance to the knowledge 

 of the lower animal world were early ascertained (such, for 

 example, as the process of division and the formation of 

 bud-like structures), and that, Avith the advancing diffusion 

 and improvement of the microscope, and the lively interest 

 that was directed towards the Infusorial world, the field of 

 observed phenomena has become a very extensive one. 



* Translated by W. S. Dallas, F.L.S., from the ' Archiv fiir Natur- 

 geschichte,' Jahrg. xxvi. p. 3o3. 



Ann. & Mag. N. Hist. Ser. 4. Vol.\x. 8 



