ZOOLOGY. 513 



the latter. The water itself is a digesting and respiring 

 mucus. 



3154. The nerve-cells have an internal cavity, from 

 the surface becoming oxydized and consequently con- 

 verting itself into a denser layer, or into tegument. This, 

 however, can only take place at the expense of the 

 internal mass, as being that alone which abuts against 

 the external parietes and becomes rigid. 



3155. As the animal life is not simply a single act of 

 rigi din* cation, but a repetition of the same, alternating 

 with solution, so must the Protozoon again replace the 

 mucus-granules which have been disposed of from its 

 interior ; it must eat. 



3156. It is a matter of indifference for the philosophy, 

 whether the reception of food is effected by one or several 

 mouths. There are Acalephse and even Intestinal worms 

 (Entozoa), which absorb by several mouths, almost like 

 plants. 



3157. But in the animal the mouth or mouths is or 

 are definite organic openings, not merely interspaces or 

 pores as in the plants ; for they rank in the signification 

 of the blossoms, or of composite parts. 



3158. It can be therefore said that every animal hath 

 a mouth or mouths, and consequently a stomach or 

 stomachs. 



3159. Their motions consist in abbreviations or strait 

 enings of the cyst. Indications can scarcely be present 

 of the secretions of higher organs, such as the intestine, 

 vessel, branchiae, liver, and such like parts. 



3160. On the contrary, developments of the tegument 

 and nerves may occur, the former as cilia which serve also 

 as organs of motion and as branchiae, the latter as ocular 

 points or rudimental eyes ; for both are none other than 

 nervose tegument. The mouth of these animals is stiU 

 passive, and subordinated to the water. It is surrounded 

 only by cilia, which by the vortices produced by their 

 movements in the water, impel or draw the latter into 

 the mouth and with it the food. Such animals are called 

 Infusoria. 



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