THE ANNALS 



AND 



MAGAZINE OF NATURAL HISTORY. 



[THIRD SERIES.] 



" perlitora spargite museum, 



Naiades, et circdrn vitreos considite fontes : 

 Pollice virgineo teneros hie earpite flores : 

 Floribus et pictum, divae, n plete canistrum. 

 At vos, o Nymphae Craterides, ite sub undas ; 

 Ite, recurvato variata coral lia trunco 

 Vellite muscosis e rupibus, et mihi conchas 

 Ferte, Deae pelagi, et pingu i conehylia sueco." 



N.Parthenii GiannettasH Eel. 1. 



No, 19. JULY 1859. 



I. — On the Metamorphoses of the Vorticellse. 

 By M. Jules D'Udekem*. 



The history of the development of the Infusoria has re- 

 mained one of the most obscure questions in natural science. 



The older authors, who had but very imperfect means of ob- 

 servation at their disposal, took little note of it, and this only 

 with a view to one object — namely, to prove the existence of 

 spontaneous generation. The inutility of their efforts is well 

 known. Modern naturalists have observed the Infusoria rather 

 under the point of view of zoology than of physiology ; and it is 

 really only within the last few years that the history of the 

 development of the Infusoria has acquired a prominent place, 

 and that observers of the first rank have given their whole atten- 

 tion to it : hence we may hope that this important question will 

 ere long make striking progress. 



My purpose in this essay is to examine carefully one of the 

 most controverted points in the history of the development of the 

 Infusoria — the metamorphosis of the species of the family of 

 Vorticellina into the corresponding species of Acineta. 



Before giving the results of my own observations, I shall 

 endeavour to trace, as concisely as possible, the history of the 

 subject I intend to treat. 



* From the * Journal de la Societe Medicale de Bruxelles.' Translated 

 by Arthur Henfrey, F.R.S., &c. 



Ann. &^ Mag. N, Hist. Ser. 3. Fo/.iv. 1 



