Dr. C. F. J. Lachmann on the Organization of Infusoria. 115 



Infusoria, so as by this means, as also by reference to the other 

 systems of organs to be observed in the Infusoria, to support 

 my opinion previously expressed regarding the structure of these 

 animals ; and in the exposition of the portions of the develop- 

 mental history of the Infusoria at present known, to refute the 

 above-mentioned opinion of Stein. 



Although the Vorticellre were amongst the first Infusoria dis- 

 covered by Leeuwenhoek in 1675*, and from their attachment 

 by means of a stem, appear to be for the most part more access- 

 ible to observation tliau many of the other free-swimming In- 

 fusoria, yet their external coarser structure remained very im- 

 perfectly known up to the time of Ehrenberg, as is proved at 

 once by the great changes of place {Iryfahrten) in the systems of 

 zoologists which had to be made, especially by certain develop- 

 mental forms of them, which are so admirably brought together 

 by Ehrenberg in his great work on the Infusuriaf, 



Before the time of Ehrenberg, authors regarded the Vorti- 

 cellce as animals of somewhat the form of a hollow hemisphere 

 or bell fastened by its convex part to a stalk. In front of 

 the supposed opening of the hollow bell (Ehrenberg first showed 

 that this was closed, and that there was only a small opening 

 on the side of the surface closing the orifice of the bell 

 {Stirn) leading into its interior), a vortex was seen to be pro- 

 duced, which drew all small particles suspended in the water 

 to the bell ; but nevertheless none of the authors could })ersuade 

 themselves into the belief that in this case small particles were 

 actually taken up or eaten, even O. F. Miiller asserting J, " In 

 omnibus meis observationibus ne minimum animalculum vel 

 moleculam unquam devorari — vidi. Pelliculas vegetabiles tan- 

 gere et quasi rodere amant {Vorticella) ; aquam vero nuti'itione 

 eorum sufficere facile persuadeor." With regard to the mode 

 in which this vortex was produced, of course the opinions were 

 for a long time by no means satisfactory. In many, the cilia 

 producing this movement were not yet found, so that Wrisberg§, 

 and even Agardh || and Wiegmann^, explained the attraction of 

 the smaller Infusoria towards the bell of the Vorticella by a 

 power of fascination like the celebrated one of the Rattlesnake ; 

 and Bory de Saint Vincent constituted a peculiar genus [Conval- 

 larina) for theseaciliated Vorticellce^^ . In others, some, but not 

 all, of the cilia surrounding the anterior opening were detected; 



* Philosophical Transactions, 1676. 



t the Infusiousthierchen, pp. 275 and 286. 



X Aninialcula Infusoria, p. xii. § Observat. Infus. p. 63. 



II Verhandlungen der K. Leop. Akad. ii. 1. p. 135. 



% Ibid. iii. 2. p. 557. 



** Dictionnaire Classique, iv. p. 412, 



8* 



