FRIED RICH S TEIN, 1 849- 1 8 5 4. 2 1 



cules, and from whom also we have received that scheme of classification 

 of the Ciliate section of the class that obtains the widest recognition at the 

 present day, and is mainly adopted in this volume. It is almost super- 

 fluous to add that the authority here referred to is none other than 

 Friedrich Rittcr von Stein, who, after his first contribution to the literature 

 of this subject in the year first named, may be said thenceforward, and up 

 to the present day, to have made a life-study of the history, habits, and 

 organization of the representatives of this highly interesting group. The 

 earliest published results of this eminent observer are specially remarkable 

 for their association with a theory relating to the development of the 

 Vorticellidae, which commanded at the time almost as large a share of atten- 

 tion and adverse criticism as followed upon Ehrenberg's polygastric inter- 

 pretations. Instead of accepting Acineta and its numerous allies, collected 

 together in this treatise under the title of the Tentaculifera, as animalcules 

 possessing an independent history and organization. Stein was led, through 

 their frequent occurrence in company with certain species of Vorticellidse, 

 and by his observation of the production by some AcinctcB of Vorticella- 

 like ciliated embryos, to regard these organisms as developmental con- 

 ditions only of the latter. In accordance with this interpretation, the 

 Podophryafixa of Ehrenberg was pronounced by Stein * to be a transitional 

 or acinete phase of Vorticella microstoma ; Acineta mystaciua, that of 

 Vaginicola crystallina ; and the form here included under the name of 

 Podophrya lemnarum as a similar condition of OperciUaria mitans. Addi- 

 tional instances in support of this Acineta theory were brought forward by 

 Stein in the ' Zeitschrift fur Wissenschaftliche Zoologie ' for February 1852, 

 its most extensive application and amplification being, however, embodied 

 in his separate treatise ' Die Infusionsthiere auf ihre Entwickelunggeschichte,' 

 published at Leipzig in the year 1854. This volume, notwithstanding the 

 fact that its associated Acineta theory was shortly after disputed, and 

 ultimately abandoned by Stein himself, still constitutes what may be 

 almost regarded as a monograph of the Vorticellid^e and Tentaculiferous 

 section of the Infusoria. In addition to embodying the most accurate 

 account and delineations of the form, structure, and developmental pheno- 

 mena of numerous representatives of these groups that had yet appeared, 

 similar details concerning various Holotrichous types were likewise included; 

 the multiplication of Colpoda atcullulus, through encystment and the sub- 

 division of its substance into two, four, or eight spore-like bodies, as 

 amply described later on, being among the most important of these supple- 

 mentary data thus recorded. The supposed relationship of the twelve or 

 more acinete types described by Stein to an equivalent number of Peritricha, 

 including representatives of the genera Vorticella, Epistylis, Opcrcularia, 

 Zoothamniicm, Cothurnia, Vaginicola, Spirochona, and Ophrydiian, is re- 

 ferred to at length in the descriptions hereafter given of the Acinetae as 

 independent organisms. 



* Wiegmann's ' Archiv fur Naturgeschichte,' 1849. 



