Prof. Ehrenherg's Researches on tlte Infusoria. 219 



talent, such as Treviranus and Oken, take up the question, where, 

 if it were possible, they ought to have ended, and assume at 

 once the existence of a mysterious power inherent in organic 

 matter of generating infusory and other molecular animalcules, 

 which form by their aggregation all organic living forms, and 

 into which the latter are, at the cessation of their proper vitality, 

 again resolved ; we cannot help referring them to the well known 

 maxim of Bacon, that " Homo naturae minister et interpres 

 tantum facit et intelligit quantum de natura ordine re vel mente 

 observaverit : nee amplius scit, aut potest." 



The observations of Dr Ehrenberg have not only given an 

 additional extension to the great principle of Harvev, omne 

 vivum ex ovo ; but have, by a connected train of ocular de- 

 monstration, proved the existence in this class of the whole three 

 species of generation, the viviparous, the oviparous, and the 

 geramiparous, and even of the simultaneous exercise of two of 

 these in the same individual, at different epochs of its existence. 

 Waiving at present the corroboration which this might give to 

 the view of infusory animals forming a parallel series to their 

 more apparent prototypes, let us proceed to state shortly a {q\v 

 examples of each of these varieties. 



In the interior of the Rotifer vulgaris we often see young 

 animals of a diminutive size (that of the parent varying from 

 ^\h to ^\h of a line), perfectly formed, and near the period of 

 exclusion, which already possess the two red points (eyes) near 

 their anterior extremity, and a distinct mouth and head. They 

 assume various postures in the interior of the parent trunk, 

 being at times coiled up in a spiral form, or extended to their 

 whole length. These same foetus, if we may so call them, Dr 

 Ehrenberg has seen excluded in a living state from the parent. 

 All the individuals of the Hydatina are hermaphrodite, possess- 

 ing the completely formed male and female organs. The fe- 

 male consists of an ovarium, which, when in the unimpregnated 

 state, is an oval perfectly transparent bilobed bladder-like body, 

 closely embracing the lower part of the intestinal tube. When 

 in an impregnated state, it increases very much in size, being 

 augmented by the addition of two or more oval appendages, so 

 that the whole mass fills the greater part of the posterior half 

 of the body of the animal. When quite ready to burst it as- 



r 2 



