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If we at the present time cut up a fresh-water polyp into fifty little . 
bits, there will be developed therefrom in a few weeks just so many 
complete polyps. Every little bit of the cup-shaped body at once 
grows up again into an entire polyp. The cell-souls of all the 
individual nerve-muscle-cells are completely alike. 
The nerve-muscle-cells of the hydra are therefore, as the 
Berlin housewife says, “maids of all work.” Each individual 
performs in the economy of this little polyp all the various duties 
which in the higher animals are distributed among muscle, nerve 
and sense-cells of different kinds. All these last widely differing 
sorts of cells consequently, have arisen by means of division of 
Jabour from simple nerve-muscle-cells. 
The next result of this division of labour is shewn us by the 
umbrella-shaped sea-bells, or Medusz, which are in fact nearly 
related to the hydra polyps, but are considerably more highly 
developed. Whoever has spent a few weeks at the sea-side has 
doubtless at times seen shoals of these beautiful bell-shaped jelly- 
soft creatures swimming about; and if anyone in bathing has 
come into disagreeable contact with them, he will remember the 
unpleasant burning sensation which was thereby excited, like 
touching a stinging-nettle. The larger class to which the medusz 
belong, are therefore called ‘“Sea-nettles.” If now with the aid 
of a large glass vessel we cautiously capture such a medusa, 
and if we accurately examine its bodily structure, we discover at 
once specialised soul-organs. On the edge of its umbrella-shaped - 
body real eyes of simplest kind and hearing bladders are keeping 
watch ; and attentive nerves communicate intercourse between the 
sensory-cells and the muscle-cells which work the powerful swimming 
motions of the medusa. Only here muscles and nerves stand in 
most intimate connexion with their original seat, the outer skin ; 
and a veritable brain, as a unifying central organ of the whole soul- 
apparatus, is still wanting to the medusze. Compared with the 
simple, diminutive, stationary hydra polyp, the great beautiful 
lively medusa seems to us undoubtedly a far higher and more 
consummate animal. And yet these two forms of animals, which 
were formerly placed in quite different classes, stand in the closest 
