618 Marvels of the Universe 
such a minute creature is 
able to find its source of 
livelihood ; but it must be 
remembered that the 
sticklebacks usually  fre- 
quent ponds and still water 
and are generally plenti- 
ful; so of the many thou- 
sands of young hatched, 
there is every chance of 
some finding their goal, 
more especially as_ their 
abundance is probably due 
to their being distasteful to 
their enemies. At this 
stage the swimming feet 
are undeveloped, — their 
function being undertaken 
by two pairs of bristle-like 
limbs. These impart to 
the larva a darting motion 
similar to the water-fleas. 
A powerful pair of triple- 
barbed hooks, or foot-jaws 
(which are replaced at a 
later stage by the suckers 
before mentioned), answer 
the purpose for attachment 
to the fish, and it was by 
their aid that the young 
larva cut its way out of 
the egg. 
The young Argulus now 
enters upon its  meta- 
morphosis by successive 
changes of form and 
structure, to intimately 
describe which would not 
He Ge net eo large, (buthin’ ciher vesectel closely urcecmme lea i iepnaten eTTRe reree ohn am Conca UD LC COD 
length of life is probably over six months. Arguli have been known to live in salt water, of this article . but at 
though they are usually to be found en fresh-water fish. 
Photo by} (Ff. Noad Clark. 
THE ADULT MALE ARGULUS. 
F each stage interesting and 
remarkable events take place in its life-history. On about the twenty-fourth day the Argulus has 
cast off the rudiments of its early stages of existence and reached the perfect state. This progress 
has been accompanied by a series of moults which continue to take place at intervals throughout 
life. The cast-skin is a replica of the body it has left, the minutest structures being retained in 
the cast. 
About the middle of June, when fish are plentiful, as many as a dozen Arguli have been found 
on a single fish, and nearly all had one or more attached. In captivity, the Arguli, if numerous, 
will attach themselves to the number of thirty or forty on one fish. Needless to say, the host lives 
