THE CARPS 105 
For the first eight or nine days the young roach 
grows exclusively at the expense of the food in the 
yolk sac, but about the ninth day the mouth becomes 
open, and he commences to feed, the food in the yolk 
sac now being practically exhausted. 
At three weeks old the larva has grown to more 
than twice the length he was when hatched, and the 
gas bladder is now sausage shaped. 
At the end of three weeks a bud appears at the 
right-hand top corner of the single-chambered gas 
bladder. This bud rapidly increases in size, and within 
a week has formed the front half of the constricted gas 
bladder of the roach. A glance at the photographs 
facing p. 106 will illustrate this point better than 
further description. 
At six weeks the roach is almost a perfect fish, and 
only the rudiments of the primitive fin remain. Plenty 
of focd is now all that he requires, and until the autumn 
the larvee grow rapidly. With the cold weather, food 
becomes scarce, the digestive juices in the stomach cease 
to flow, and the growth of the fish is arrested until the 
weather again becomes warm. At the end of the first 
year, most roach fry are about an inch and a half in 
length, though they may have grown to twice this size 
under exceptionally favourable circumstances. 
The carp is not a fish of much importance in our 
country, but in Germany its cultivation is systematic- 
ally undertaken. Suitable carp food is bred in ponds, 
liberally supplied with sewage. Into these ponds the 
