THE MEDUSA. 21 



complete liberation, present themselves as free and inde- 

 pendent animals {Ephjrci) of the Medusa family. In the 

 polypoid animal which as it were includes the series of 

 piled-up Medusa-larva, (if they may be correctly so called 

 which are a younger stage in the development of the 

 Medusce^ such an advance to the perfect form has never 

 been observed ; and that it should attain the same per- 

 fection that the larvae do, is, in consequence of the size it 

 has already attained and its relations, altogether impro- 

 bable ; that it might reach this goal by following another 

 course of development is so much the more improbable 

 as we see in the rest of organic nature, like pass only 

 into like.* What the nature of this creatm^e consequently 

 may be, is a question now to be solved, but we require 

 to enable us to do this, in the first place, a precise know- 

 ledge of its structure. Sars declares that this polypiform 

 animal simply incloses an internal cavity of the same form 

 as the exterior of the body ; it is closed superiorly by an 

 annular membrane, which is placed within the circle of 

 tentacles, and which can be so contracted as completely 

 to close the opening, or so expanded as to form one, 

 equal in size to the diameter of the body. This opening 

 in the annular membrane, which is the entrance into the 

 internal hollow of the bell-shaped body is termed by Sars 

 the oral orifice, but certainly erroneously so. Of internal 

 organs Sars has observed only fom' roundish prominent, 

 longitudinal ridges proceeding at equal distances from 

 each other, from the bottom of the bell to its border, and 

 the extremities of which, when they reach the annular 

 membrane at the mouth of the bell, appear like four small 

 round holes in it, (vid. Sars in Erichson's Archiv, Ister 

 H. Tab. i, fig. 31.) But here I beg leave to add some 

 remarks and observations which I made during a long 



* That tliey have the power of again affixing themselves, and that a new 

 series of medusa-larva should a second time be developed from them can be 

 the less supposed, since Sars has shown that even the youngest individuals 

 which have become detached, before the transverse wrinldtng has taken 

 place, can only under extreme necessity re-affix themselves, and then very 

 loosely ; and all of them are not able even to do this. 



