ACALEPHvK 
109 
When the Medusa; travel, their convex part is always kept m 
advance, and slightly oblique. If they are touched while swimming, 
even lightly, they contract their tentacula, fold up their umbrella, 
and sink into the sea. Like Ehrenberg, M. Kolliker thought he dis- 
covered visual and auditory organs in an Oceania, and Gegenbauer 
thought he detected them in other genera, such as RMzostoma and 
Pehgia. The eyes are said to consist of certain small, hemispherical, 
cellulose, coloured masses, in which are sunk small crystalline globules, 
the free parts of which are perfectly naked. The supposed auditory 
a Pparatus is seated close to these organs; they are small vesicles 
filled with liquid ; the eyes having neither pupil nor cornea, and the 
cars without opening or arch. 
But it is in their reproduction that these evanescent beings present 
the most marvellous phenomena. At one period of the year the 
Medusse are charged with numbers of very minute eggs, of the most 
lively colours, which are suspended in large festoons from tlieir 
floating bodies. In some cases these eggs develop themselves grafted 
to their- bodies, and are only detached at maturity. In other cases 
the larvae produced bear no resemblance to the mother; they are 
elongated and vermiform, broad at their extremity ; we speak ot the 
microscopic leeches, which have vibratile cilia, scarcely perceptible, by 
■which they execute the most lively motions. At the end of a certain 
thue they are transformed into polypes, and furnished with eight 
tentacnla. This preparatory sort of animal seems to possess the faculty 
el reproduction by means of certain buds or tubercles which develop 
themselves on the surface of the body, and also by filaments which 
start up here and there, so that a single individual originates a 
numerous colony. This polype is subjected to a transformation still 
nr°re remarkable ; its structure becomes complex, its body articulate, 
a nd it seems to be composed of a dozen disks piled one upon the 
°tlier, like the jars of a voltaic pile ; the upper disk is convex, and is 
Se parated from the colony after a convulsive effort ; it becomes free, 
a nd an excessively small, star-like Medusa is the result ; every disk, 
that is, every individual, is isolated one after the other in the same 
banner. 
Thus of the sexual zoophytes which propagate their kind according 
j° the usual laws; but others engender young which have no resem- 
'flnnce to the parent zoophyte at all : in this respect they are neuter, 
