46 THOUGHTS ON ANIMALCULES. 



a drop of a solution of carmine* in the water between 

 the plates of glass containing the Vorticella? : the fluid 

 in which they are floating now appears turbid, and full 

 of grey particles, which are thrown into rapid motion 

 by the vibrations of the cilia, and currents are seen 

 passing to and from the mouth of the animalcules. In 

 a few minutes the water gradually becomes clear, and 

 several round spots of carmine are apparent in the body 

 of each of the Vorticellae, (pi. in, figs. 3, 6). We have, 

 in fact, caused their little stomachs to be filled with 

 colouring matter, and can now distinguish their number 

 and arrangement. If the body of the Vorticella were 

 a mere vase or cup, or a simple cavity like the digestive 

 sac of the Polype, it is obvious that the carmine must 

 have collected into a single ball or mass ; but this is not 

 the case ; on the contrary, the colour appears in distinct 

 round spots, from having accumulated in globular cells ; 

 and, by careful investigation, the tube connecting these 

 cells may be detected. 



* Sap-green, indigo, or carmine may be employed ; it is necessary to 

 use colour free from adulteration. The idea of colouring the water con- 

 taining animalcules, with the view of rendering their transparent organs 

 more distinct, originated with M. M. Trembley and Gleichen ; but no im- 

 portant results were obtained by the experiments of these observers. In 

 the hands of M. Ehrenberg this method of investigation proved emi- 

 nently successful, and led to the discovery of the internal structure of the 

 Polygastria. 



