THE CARPS 103 
To return to the roach. Roach eggs take seven to 
fourteen days to hatch with the water at a temperature 
of 59°F. If the eggs are attached to the vegetation 
near the surface, the extra light and warmth hurries 
on the hatching. If they are placed deeper in the water 
hatching is somewhat delayed. 
When the roach larva escapes, he is about a quarter 
of an inch in length, and has an arched back and turned- 
up tail. Exhausted with the exertions of struggling out 
of the egg, he sinks to the bottom, but in an hour or two 
he has gained sufficient strength to swim, and he comes 
up to the surface with a circular wriggling movement. 
This peculiar method of progression is due to the tail 
having an upward tilt. 
The larva at this stage has no gas bladder, and so 
if he stops swimming he immediately sinks, but if he 
reaches the surface and still continues to swim, he 
twirls round and round, making rings on the water. 
When roach are hatching in large numbers on a warm 
still day, these rings are visible all along the banks of 
pond or river. In six to twelve hours the larval roach 
has become quite straight, and now swims about rather 
more, but he still has no gas bladder, and has to swim 
all the time, or sink. When, however, he touches any- 
thing, or comes up to the surface of the water, he now 
appears to be held up by what I thought to be capillary 
attraction, though since it has been suggested to me 
that he is really held up by the mucus on his body. 
At this stage many of the larvee rest at night in a per- 
