380 EVENINGS AT THE MICROSCOPE. 



orifice of tlie urn, and more are joining tliem ; wo see 

 the}' are tentacles, protruded in a loose bundle, just as 

 the poljpe emerges from the cell. 



It is a somewhat slow process ; but at length the 

 fleshy mass squeezes itself forth, as if pushed out by 

 some contractile force behind ; while we see the fluids, 

 carrying granules, run into the parts of the tentacles 

 which are already free. The embryo is liberated. 



For a few seconds it appears helpless, and falls 

 through the water in a collapsed state, so that we 

 cannot discern its proper form. It gives a spasmodic 

 contraction or two, feeble at first, then more vigorous ; 

 the tentacles lengthen, the bod}' expands, and — lo ! it 

 is not a polype, but a Medusa ! 



And now take your eye for a moment from the 

 microscope, and glance at this glass jar, in which the 

 oarweed with its colonj^ of Zoophytes has been standing 

 for a few hours. Hold it between your eye and the 

 light ; do you not see tliat the water is alive with tiny 

 dancing atoms ? Hundreds are there, playing and 

 pumping through the fluid with a sort of flapping 

 motion, which, when you get on sidewisein clear view, 

 will not fail to remind you of the flac'o-ino' flio-ht of some 

 lieavv-bodied, lono;-wino;ed bird. These are the Me- 

 dusa-shaped progeny of the Laomedea. 



But let us return to the one of which we have jusr 

 witnessed the birth, and which is still flapping to and 

 fro in the narrow glass trough. Yon see a pellucid 

 colourless disk or umbrella of considerable thickness, 

 about one sixtieth of an inch in diameter in its average 

 state of exj^ansion. Its substance has a reticular aj")- 

 pearance, probably indicating its cellular texture. In- 

 ternally, the disk rises to a blunt point in the centre. 



