140 THE WORLD OF THE SEA 
numerous parts, and then we should have phenomena exactly 
similar to those which are presented in the lives of the meduse. 
All medical men now know that the Zenza, an articulated 
tapeworm, has larve very different to the perfect creature, and 
which have the power of producing other larve like themselves. 
Thus these curious animals are simple at one period of their 
lives, compound at the second stage, and return to their simplicity 
at a third. Never can it be too often said that all is changeable 
in nature; God alone being “the same yesterday, to-day, and 
forever: 
It is remarkable with regard to butterflies that they pass suc- 
cessively through such opposite states ; at one time vitality is very 
apparent and exuberant, at another latent and all but extinct; now 
they are in movement, now in repose. The egg is immovable, the 
caterpillar crawls, the chrysalis sleeps, the butterfly dances in the 
air; and each time of action is preceded by a period of repose, 
according to a great law in physiology. » Look, for instance, at 
the silkworm, each time she undertakes to clothe herself in a 
new vesture she remains in a torpor, preparing for a new life by 
a semblance of death. Quatrefages remarks that the tendency to 
metamorphosis increases as we descend in the scale of life. 
Many of the medusz produce an acute pain when touched, like 
the sting of a nettle, to which property they owe their name of 
sea nettles. 
One of the most remarkable of the species is the Lazry medusa, 
the terror of bathers. This creature is like a pretty brown um- 
brella, divided and festooned, with a thick pedicle and a great 
number of arms, long and ribboned, carrying after them floating 
hair, the more dangerous since it is well nigh transparent. Any 
one who imprudently ventures into the midst of these poisoned 
filaments soon feels the most insupportable agony. The medusa, 
when escaping, often leaves behind it these hairs, which become 
detached, and, though they are separated from the creature, they 
still retain their stinging power, as though they would revenge 
themselves for their isolation. The stinging organs of the medusa 
are very tiny cells disseminated in their skin, upon which they 
form little protuberances. They may be noticed round the ex- 
