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 larvae rest at night in a per- 



