ASEXUAL REPRODUCTION. 



189 



supply. In the last century, the Abbe Trembley delighted 

 himself and others by the often repeated observation, that to 

 get many hydra polypes out of one, the simplest and quickest 

 way was to cut it in pieces. Though the fragment be very 

 small, it will reproduce the whole, provided always that it have 

 to start with fair samples of the different kinds of cells in the 

 body. The same may be done any day with the much larger 

 sea-anemones. So the earthworm, curtailed by the spade, does 

 not necessarily suffer loss, though it suffer pain. The head por- 

 tion grows a new tail, and even a decapitated portion may 

 reproduce a head and brain, not that this is saying much for 

 these. 



§ 2. Regeneration. — Spades and knives are not exactly 

 instruments of nature, but they have their counterparts. Fight- 

 ing with a rival a crab may lose its claw, or the same may 



The Formation of a Sponge Colony {Olynthtis) by 

 budding. — After Haeckel. 



happen in the frequently fatal moulting, which seems almost 

 like a mistake in nature. Slowly, however, forgiving nature 

 makes good the loss ; the cells of the stump multiply, and 

 arrange themselves in obedience to the same necessities as 

 before, and a limb is regenerated. Many an appendage among 

 the lower animals is from time to time nipped off, only to be 

 grown again. A snail has been known patiently to regenerate 

 an amputated eye-bearing horn twenty times running. Sometimes 

 one is tempted to think that the animals almost understand that 

 it is better for one member to perish than for the whole life to be 

 lost, so readily does a starfish surrender an arm, or a lizard its 

 tail. Yet it must be recognised that animals, like men, are often 

 wiser than they wot of. In the panic of capture, strong con- 

 vulsions may occur, which surprise and perhaps shock the 



