TNPrsORTAL AlflMAICTTLES. 37 



most evident manner, that they could not have a communicating 

 canal between the stomachs, pro\ided with an oral orifice and an 

 exti-emity directed to the mouth. 



"But it will be asked, what are these vesicles and balls of the 

 same diameter existing in the bodies of the Infusoria, and which 

 have been taken for stomachs ? This question I have continued to 

 ask myself, till an attentive and long-continued investigation has 

 enlightened me as to their origin. 



" The true Infusoria are vesicular beings, whose interior are filled 

 ■with a mucous substance ; the thickness of the membrane forming 

 the vesicle, can easily be ascertained in some of these animals ; and 

 in many species I have 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 

 oesoj)hagus) 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 siu'face 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 acquu-ed a spherical form. 

 During the formation of this ball, the stomach (for it is evident we 

 must distinguish this organ by that name) has a free commimication 

 with the oesophagus, and by means of the ciliaiy apparatus 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 likcAvise beset with cilia in the part 

 Avhich 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 substances 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 fu-st ball along with the muco- 

 sities 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. Ehi'enbei'g believe that these animals were 



