210 RAMBLES OF A NATURALIST. 



the genera Aurelia, Chrysaora, and Rhlzostoma, di- 

 gestive cavities, systems of circulation, and repro- 

 ductive oro^ans of the most characteristic nature, have 

 been discovered; while Ehrenberg, the illustrious 

 microscopist of Berlin, penetrating still further, has 

 isolated the ultimate elements of the organism, and 

 detected the existence of a sensorial apparatus, which 

 he regarded — and very probably with justice — as 

 actual eyes. 



However, among the Medusae as well as in almost 

 all the great animal families, the organic machine 

 presents very different degrees of complication and 

 perfection. Beside the genera to which we have 

 referred, there are others which, being of a much 

 more simple structure, and having no inferior ap- 

 pendages, appear to be in a condition of the most 

 marked degradation, and, therefore, would seem to 

 warrant the opinion advanced by some observers, 

 that they may, under certain restrictions, be cha- 

 racterised by Reaumur's designation of vivified jelly. 

 As no organs of reproduction had been discovered in 

 the Eudorea or ^quorea, Eschscholz, a German 

 naturalist, was of opinion that the Medusae might, 

 consequently, be divided into two groups, distin- 

 guished by the presence or absence of these organs. 

 M. Edwards has demonstrated that this distinction 

 was based upon incomplete observations ; he found 

 in the iEquorea nearly all the organs which had 

 been discovered in the Aureha; and he further 

 showed that the sexes were distinct and recognisable 

 by characteristic marks. It will readily be under- 

 stood that these results were of the utmost import- 



