64 LIFE AND HER CHILDREN. 
animals of the sea, are devoured by this ferocious 
lasso - thrower as he moves lazily through the 
water expanding and contracting the rim of his dome; 
and if it were not that he and his fellows are the 
chief food of whales and porpoises, they would com- 
mit terrible havoc in the o:ean, as they travel in 
shoals of thousands together. 
And now at certain seasons of the year, when at 
night the sea glows with their phosphorescence/"" some 
of these large wanderers drop from under their huge 
umbrella something which looks like a shower of 
dust. This shower is composed of a number of 
minute jelly-bodies (a, Fig. 24) swimming by means 
of lashes or cilia, and something like those which come 
from a sponge (see p. 38). They have been hatched 
from eggs within the umbrella of the jelly-fish, ana are 
setting off into life for themselves. After a few davs 
four curious knobs (b, Fig. 24) begin to appear upon 
them, and these increase every day till at last the 
swimming animal settles down on a rock and becomes 
o 
a small hydra feeding peacefully upon minute sea- 
animals by means of its tender threads. 
This then is the young of our jelly-fish, a common 
hydra like that of the pond ! Moreover, this young 
hydra seems to forget all about its wandering parent- 
age, and often goes on for several years budding into 
other hydras, and living as though it had never had 
anything to do with a jelly-fish. 
But at last one day a change comes over some of 
* The phosphorescence is due to a glutinous fluid exuded from the 
umbrella. This fluid, when squeezed from a large jelly-fish into twenty- 
seven ounces of cows' milk, made it so phosphorescent 'hat a letter could 
be read by the light at a distance of three feet. 
