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



We soon succeeded in getting Stein's Acineta of the Duck- 

 weed *, which he regards as the resting-form of Vorticella nebu- 

 lifera. A. Schneider first found a specimen with an embryo 

 already rotating, the escape of which we then expected with im- 

 patience ; but this, hke all the other specimens whose birth we 

 observed during the summer, escaped from our sight before be- 

 coming attached and converted into an Acineta or a Vorticella. 



Once, however. Professor Miiller, whilst searching for an 

 Acineta-hxiidi which had escaped from him, found an animal 

 which was exactly like it, swam very slowly, and at last, becoming 

 perfectly stationary, gave forth rays and grew into an Acineta. 



This observation of course increased our doubts as to the 

 correctness of Stein's view. It is true we were not certain 

 whether the animal which became an Acineta was truly an 

 Acineta-h\xd.j which, according to Stein's representations, ought 

 to have become a Vorticella, or whether it was not perhaps a 

 Vorticella already metamorphosed, which had then become con- 

 verted into an Acineta, certainly in a very different manner from, 

 that supposed by Stein. In any case, this fact could not but 

 urge us to trace the subject further. 



In the course of that summer no decisive observation was 

 made. But when I afterwards continued these observations in 

 Brunswick, Wiirzburg, Gottingen, and Berlin, and paid a close 

 attention to the organization of the families of Infusoria in ques- 

 tion, and also to that of other families, I arrived at the convic- 

 tion that Stein's view of the conversion of the Vorticellce into 

 Acineta was erroneous : that his description of the Vorticella, 

 although far better than that of his predecessors, was still very 

 defective : and that all Infusoria are neither polygastric, as 

 Ehrenberg states, nor composed of formless substance, as asserted 

 by Dujardin; but that, as already stated by Meyenf, they are 

 animals with a large digestive cavity, — which, however, must not 

 be regarded, as he thought, as the interior of a cell, but the 

 part which Meyen and most of the recent authors regard as the 

 cell-membrane must be looked upon as the parenchyma of the 

 body, — which does not represent the membrane of a cell any 

 more than that of the Polypes, — a view which has been taught 

 for years by Professor J. Miiller in his Lectures on Comparative 

 Anatomy. In the hope that perhaps they may possess some 

 interest, I venture to communicate the principal results of 

 my investigations of the Infusoria. I may therefore be per- 

 mitted to describe the digestive apparatus of the Vorticella 

 somewhat in detail, and to compare it with that of the other 



* Die InfusioBsthierchen auf ihre Entwickelungsgeschiclite untersucht, 

 1854, p. 59. 

 t MuUer's Archiv, 1839, p. 74. 



