46 M. Ehrenberg'^s Researches on the Infusoria. 



sores, and had often witnessed its mode of reproduction, it was 

 nevertheless not till a late period that he ever observed a 

 great double organ, placed in the interior of the body, the 

 knowledge of which, he conceives, is not more important for 

 the elucidating the anatomical structure of this animal, than 

 for the science of physiology in general. Its existence, he 

 believes, evidently proves, that, besides the organs of diges- 

 tion, of respiration, and the fernale genital apparatus, there 

 exists in these Infu sores other organs still, which can belong 

 neither to the vascular nor nervous system, but which pro- 

 bably constitute a portion of the generative apparatus, by 

 which the animal impregnates itself. For a long time, he 

 had observed in the bodies of the greatest number of Poly- 

 gastrica isolated vesicles, which often contracted rapidly and dis- 

 appeared, and then after a time dilated anew. But as these 

 small vesicles often exactly resembled those which were filled 

 with nutritive matter, he regarded them as stomachs, which the 

 animal had perhaps alternately filled and emptied, and he more- 

 over believed that perhaps all the vesicles of the stomach had 

 this power. Thus it was, that frequently in the figures which 

 accompanied his earlier works, transparent vesicles may be per- 

 ceived placed at the side of the intestine, and which at other 

 times are not so indicated. In the Trachelius anas, they in- 

 variably appeared so large, that he was led to consider them as 

 particular stomachs, remarkably voluminous, and filled with wa- 

 ter, and he always thus represented them. After the observa- 

 tions we have alluded to at the commencement of this paragraph, 

 the Professor latterly directed his attention to these vesicles, en- 

 dowed with this singular faculty of sudden contraction and di- 

 latation, and to his surprise discovered that they existed to the 

 number of three or more, though usually to the number of two 

 only, in a fixed and determinate place of the body of the animal. 

 That he might the more accurately study these organs, he 

 took a certain number of the Paramecia aurelia, and subjected 

 them to pressure between two glass-plates, at the same time ta- 

 king care to place between them some threads of Confervae, to 

 prevent their too close approximation: he thus forced these 

 little creatures to remain stationary, and flattened them a little, 

 without bruising them. In this way, he speedily succeeded in 

 discovering eight conduits or canals, which shot in rays from 



