104 ASSOCIATION OF ORGANISMS—THE WEB OF LIFE 
are transformed into fishing-lines that catch food, and at the same 
time are so well provided with stinging-cells as to effectively keep 
off enemies. There are also digestive individuals, which devour 
and digest the animals caught by the fishing-lines. Some mem- 
bers are reduced to tentacles, ministering to the sense of touch 
(and possibly smell); others again are in the form of protective 
plates, covering and sheltering adjacent in- 
dividuals. And there are also egg-produc- 
ing members of the colony which may be 
liberated as little meduse, thus promoting 
dispersal. In different species there are 
considerable variations in detail, and the 
actual arrangements in one case (Stephalia 
corona) are shown 
in fig. 1093. 
CotoniaL Moss- 
Potyres (PoLyzoa). 
—With a single 
exception the mem- 
bers of this group 
produce colonies by 
budding, after the 
fashion of Hydroid 
_Fig. 1og2.—Diagram of various in Z oophytes, for 
dividuals in a colony of Compound : P 
Jelly-Fish (Siphonophora), central which they are Fig. 1093.—A Compound Jelly- Fish 
cavity of colony indicated in black. E : (Stephatia corona), reduced. 2, Float; 
Ft, Float; s, swimming-bell; 2, 2, SOMetimes MIS- 5, swimming-bell; g, gas-conducting indi- 
Ggetve divin Z2s rnc taken, though in Winticsmaldueaeindiul ma 
aula Acai ome fo reality much higher ic," ° ml Meme 
in the scale. Some 
of the members of such a colony may be greatly specialized for 
various purposes (fig. 1094), e.g. they may be modified into rounded 
receptacles (ovicells) in which the eggs develop till the time of 
hatching. In certain species there are bird’s-head individuals, 
which execute vigorous snapping movements, the object of which 
is extremely doubtful. Cleanliness is possibly promoted, or per- 
haps the attacks of small parasitic forms may thus be warded off. 
It has also been noticed that the powerful jaws often succeed in 
catching little worms, crustaceans, &c., apparently holding them 
tenaciously till they die and decompose. The suggestion has been 
made that the decayed fragments of these victims are carried by 
