ATKINS THE SALMON AND ITS ARTIFICIAL CULTURE. 253 



After the eggs were placed in the hatching-trays it was easy, by count- 

 ing the number of eggs in a row across the tray, to compute the number 

 in each. A tray of the size most used, two feet long and one foot wide, 

 held about 4,000 of them when they were evenly spread in a single 

 l«yer. The whole number was about 1,560,000. In taking them the 

 eggs of each fish had, in the majority of cases, been kept by themselves 

 as a distinct lot, the record showing when and how taken, and any note- 

 worthy facts about the parent fish or the manner of treating the eggs.* 

 In a number of cases, for the purpose of trying a series of experiments, 

 the eggs of a single fish were divided into several lots. These were all 

 kept separate in the hatching-troughs, and, although the fortunes of the 

 season frustrated a portion of the experiments, others afforded interest- 

 ing results. 



The evidences of maturity of a spawning salmon commonly observed 

 are, a soft condition of the abdomen and the flow of eggs under pressure. 

 The latter is really less trustworthy than the former, for the fish ap- 

 pears to have the power of constricting the vent so that a man's strength 

 is hardly sufficient to press the eggs out. When a gravid fish is held 

 up by the tail, if the eggs are free from the ovary they run down toward 

 the head, distending the anterior portion of the abdomen and leaving 

 it flabby and loose near the vent. If the eggs are still adherent to the 

 ovary they, of course, retain their position and the abdomen its external 

 shape. The protrusion of the vent, which is one of the marks relied on 

 by some breeders of trout, fails in the case of salmon. In many instances 

 maturity of the eggs is accompanied by the temporary drawing in 

 of the vent quite out of sight, and by its firm constriction. This is 

 nearly always the case while the fish is struggling, whether during ma- 

 nipulation or before, and may, to a certain extent, be an incidental re- 

 sult of the efforts of the fish to get free ; but it sometimes continues 

 after muscular action has ceased in every other part. 



I think it can be laid down as a general rule that at the time when a 

 female salmon voluntarily begins to spawn, her eggs are all ready to be 

 laid and capable of fecundation. To be sure, my observations have 

 been made on salmon under a certain degree of restraint, which may 

 have interfered to some extent with the normal development of the eggs 

 and the normal exhibition of the reproductive instincts. But in the 

 pond at Bucksport the range was so great that, as far as could be judged 

 from the actions of the fish, they felt after the first few weeks quite at 

 home ; and I have seen nothing in their behavior which indicates that 

 the degree of such interference is other than trifling. It is, therefore, 

 presumed that the maturity of the eggs was nearly the same as it would 

 have been in a state of nature. 



In the case of the salmon manipulated, nearly every one yielded at 

 once all of her eggs, except such as were packed in the anterior ])art of 



' See table 9. 



