INLAND FISHERIES. 49 



3. Can the eggs he fertilized artificially ? — From the 8tli of Jiiue 

 to the end of the month it was possible to obtain eg-gs and sperm 

 from the scallop and fertilize the eg-gs artificially. It was dis- 

 covered, after several experiments in dissecting the animals to ob- 

 tain the eggs, that if the ripe scallops were allowed to remain for 

 a few days after being collected they would of their own accord 

 discharge the eggs and sperm. The eggs Avere, as a rule, dis- 

 charged at a different time from the sperm, and, therefore, by 

 keeping the individuals in separate dishes, the eggs could be ob- 

 tained unfertilized before the sperm was extruded. In this way 

 they could, of course, be fertilized at any particular moment which 

 was desired. 



4. ^V^lat are the habits of the young fry ? —In the apjDearance 

 f)f the eggs and the characteristics of the early stages the scal- 

 lops bear a close resemblance to the clam and oyster. The eggs 

 are spherical and very small, about ^oVo inch in diameter. They 

 are fertilized in the sea-water and then immediately commence the 

 series of internal changes wliicli result in successive alterations in 

 structure and in external form of the microscopic fry. 



From the experiments in artificial fertilization, material was 

 furnished in abundance for the study of the stages heretofore un- 

 known in the case of the scallop. An account of the details of 

 the development will not be given here, but only some of the gen- 

 eral features. 



During the first 12 hours after fertilization the eggs lie motion- 

 less on the bottom. At the end of this period they commence to 

 rotate slowly at first, but with increasing rapidity. By the time 

 they are 36 hours old they swim with considerable rapidity, and 

 are constantly in motion. There is no increase in size from the 

 time the eggs are fertilized to the time they begin to SAvim. GroAvth 

 begins soon after this, however, and in the following days of 

 ceaseless activity the minute creatures are swimming in quest of 

 food. Throughout the free-swimming period they are like the 

 larvae of other forms in being very sensitive to light, and are at- 

 tracted or repelled by it according to various circumstances. By 



7 



