NUTRITION IN THE INFUSORIA. 87 



efforts, to detect the arrangement depicted in the 

 tigures given by Ehrenberg. He observed that the 

 apparent vesicles, far from exhibiting a connexion 

 with a central canal, are in fact, in a continual 

 rotatory circulation, like the coloured granules 

 which are visible in the gelatinous substance of the 

 hydra, and which themselves receive a tinge from 

 coloured food.* J. Meyen also declares his inabi- 

 lity to see these pretended intestines and stomachs ; 

 and observes that the opaque globules supposed to 

 be lodged in them, move in the interior of the body, 

 in many species with great rapidity, in the same 

 manner as the granules which circulate in the 

 joints of the chara: and what strengthens the 

 analogy, the membrane enclosing the mucous sub- 

 stance which constitutes the bulk of the animalcule, 

 has an obviously spiral structure. In the large 

 infusoria, a recipient cavity may be seen, the lower 

 end of which dilates on the introduction of food, 

 which it forms into a ball by the action of its cilia ; 

 this ball then passes out of the stomach into the 

 general cavity ; and this process being continually 

 repeated, the balls are pushed forwards and distri- 

 buted in various parts of the substance of the 

 animalcule, giving rise to all the appearances 

 described by Ehrenberg. Meyen remarks that 

 similar cavities are formed in the mucus of true 

 cellular plants, particularly in certain aquatic 



Cryptogamia.t 



The Hydatina senta, one of the largest of the 

 Infusoria, was found by Ehrenberg to possess a 



* " General Outline of the Animal Kingdom," p. 57 and 58. 

 t Annales des Sc. Nat. serie 2, xii, 122. 



