Prof, Ehrenberg on Fossil and Recent Infusoria. 123 



scopic sparks following each other in quick succession. The 

 analogy with electrical phsenomena is very close, and it is espe- 

 cially worthy of attention that evidently the smallest animals 

 give the largest sparks, in proportion to the size of their body, 

 and consequently very probably produce the greatest electrical 

 tension. 



I then mentioned the curious formation of double gems in 

 Closterium and in the Confervce conjugatce, which is figured 

 in the plates of the family of the Closterince, and I concluded 

 with the remark on the astonishing great fertility or capa- 

 city of increase of microscopic animals, according to which 

 an imperceptible corpuscle can become in four days 170 bil- 

 lions, or as many single individual animalcules as contained 

 in 2 cubic feet of the stone from the polishing slate of Bilin. 

 This increase takes place by voluntary division ; and this is 

 the character which separates animals from plants. It is true, 

 that the gemmation in plants, especially in very simple ceUs, is 

 at times very similar to the division in animals, but this re- 

 lates to the form not the formation. A vegetable cell appa- 

 rently capable of self division always became one, or contem- 

 poraneously many exterior warts (gems) without any change 

 in its interior. An animal which is capable of division first 

 doubles the inner organs, and subsequently decreases exte- 

 riorly in size. Self division proceeds from the interior towards 

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

 which also occurs in animals, proceeds from the exterior to- 

 wards the interior, and forms first a wart, which then gra- 

 dually becomes organized. 



A discussion now arose between Prof. Rymer Jones and me. 

 Prof. Jones observed, that although he had given himself great 

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

 by me of the interior organization, viz. of the ahmentary canal 

 of the polygastric Infusoria, although he had found the ex- 

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

 to discover any trace of an alimentary canal, and in Para- 

 mecium Aurelia and other species he had observed a circular 

 motion of the inner cells which could not agree with the for- 

 mation 1 had 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 



