THE JELL Y-FISH. 337 



cerned, the great object of the incessant contraction and expansion 

 being, as we have said, not so much change of place as the capture 

 and insuction of its ordinary food. The Medusae swim at all depths 

 in the sea, but as a rule they seem to prefer feeding within a 

 fathom or two of the surface, particularly if the sun is bright and 

 the sea is perfectly calm. The mouth of the Medusa is in the centre 

 of the under concave surface, and the animal's modus operandi in 

 sweeping in its food towards this orifice is not difficult to understand. 

 Stretch out your right hand, with its back or knuckle surface upper- 

 most. First expand the hand and fingers to their full extent, then 

 contract so as almost, but not quite, to close the hand, not quickly, 

 but very firmly and decidedly. Continue in this way opening out 

 and closing the hand and fingers, not quite so fast as a second's 

 beating pendulum oscillates, and you have the perfect analogue, or 

 more properly the homologue, of the Medusa's action. If you can 

 fancy an orifice or mouth in the centre of your palm, and your 

 fingers to be the fringe surrounding the jelly-fish disc, and if you 

 perform the action indicated in a tub or pool of water, into which 

 a little flour or fine oatmeal has been thrown to represent the 

 animalculae forming the Medusa's food, so much the better : you 

 will at once understand how the animalculae and food particles are 

 swept and sucked in by the current created towards the animal's 

 mouth, or gastric cavity, as it might be more properly termed. 

 When one or more of these animals comes in contact with a swimmer's 

 skin, the sensation is anything but agreeable, a feeling of indescrib- 

 able loathing and horror being engendered by the touch of the cold, 

 gelatinous mass, that you are yet conscious is not dead matter, but 

 an animated pulsating organism. But though contact with the 

 ordinary Medusa is bad enough, there is another species of jelly-fish 

 not uncommon in British waters at certain seasons, accidental con- 

 tact with which is a very serious matter indeed. These are known to 

 naturalists as Acalephce, from a Greek word signifying a nettle. They 



Y 



