56 GENERAL HISTORY OF 



noticed in this membrane an obvious spiral structure, 

 which establishes a complete analogy between it and 

 cellular vegetables. In the large Infusoria, a cylindrical 

 canal (the oesophagus) obliquely traverses the membrane 

 which forms the animal. The lower extremity of this 

 canal dilates, more or less, when the animal has taken 

 food, even till it attains the dimensions of the balls which 

 are found in the interior of these same Infusoria. 



" The inner surface of this part of the intestinal canal is 

 provided with cilia, which turn round not only the 

 alimentary substances, but also foreign bodies, till they 

 have acquired a spherical form. During the formation of 

 this ball, the stomach (for it is evident we must distin- 

 guish this organ by that name) has a free communication 

 with the oesophagus, and by means of the ciliary ap- 

 paratus found at the exterior, new alimentary substances 

 are introduced into this canal, and pushed as far as the 

 stomach, but I could not satisfy myself whether the 

 oesophagus was likewise beset with cilia in the part 

 which separates the stomach from the buccal orifice. 

 When the ball has acquired the size of the stomach, it is 

 expelled by its other extremity and pushed into the cavity 

 of the animal. It then forms a new ball, if any solid sub- 

 stances exist in the surrounding liquid. This second ball 

 is itself pushed into the interior of the cavity of the 

 animal, and drives before it the first ball along with the 

 mucosities between the two ; the successive formation of 

 similar balls, by the matter received into the animal, 

 continues in the same manner, without interruption. It 

 is the simultaneous existence of many of these balls that 

 made M. Ehrenberg believe that these animals were 



