Fossil and Recent Infusoria. . 373 



one, or contemporaneously many exterior warts (gems) without 

 any change in its interior. An animal which is capable of divis- 

 ion first doubles the inner organs, and subsequently decreases ex- 

 teriorly in size. Self division proceeds from the interior towards 

 the exterior, from the center to the periphery ; gemmation, 

 which also occurs in animals, proceeds from the exterior towards 

 the interior, and forms first a wart, which then gradually becomes 

 organized. 



A discussion now arose between Prof Rymer Jones and me. 

 Prof Jones observed, that although he had himself taken great 

 pains, yet he had never been able to see the structure described 

 by me of the interior organization, viz, of the alimentary canal 

 of the polygastric Infusoria, although he had found the external 

 forms to be exactly the same. He had not been able to discover 

 any trace of an alimentary canal, and in ParatncBciuni Aurelia and 

 other species he had observed a circular motion of the inner 

 cells which could not agree with the formation I Jiad described. 

 I answered him, that such discussions then only could lead to a 

 result when they do not merge into general but enter into special 

 cases. The mass of relations of organization, which after many 

 years of observation have been gradually established, could not be 

 brought into question by a single doubtful fact. The perfect organ- 

 ization of the wheel animalcules had been established beyond all 

 question. With regard to ParamcBciuni Aurelia, this is one of 

 those forms unfavorable to such observations ; and it had been ex- 

 pressly observed by me that I myself had not been able to recognize 

 the alimentary canal in all species of the various genera ; but on the 

 other hand it was quite evident in a very considerable number of 

 species and genera. I stated that in my present work this subject 

 had been treated of in detail, and that those forms in which the 

 relations are perfectly evident have been purposely enumerated. 

 Some of these forms I then exhibited in the drawings, and con- 

 cluded with the remark that the circular motion observed by Prof. 

 Jones had already been treated of by others, (for instance. Dr. 

 Foeke,) and had naturally been frequently observed by myself 

 The great contractibility of the body of the animalcule was, to 

 less practiced observers, frequently a cause of enigmatical phenom- 

 ena, of which continued patient observation of the object would 

 gradually bring the explanation. Thus, at times, the intestinal 

 canal of the animalcule extends at the expense of the ventral 



