218 NATURAL HISTORY OF AQUATIC ANIMALS. 



over a period of fully two months. That this is true there can be little doubt, for when the 

 females first begin to throw their eggs only a very small percentage of the whole number are ripe, 

 while the balance show every gradation to the perfectly green and immature. By frequent exam- 

 ination of individuals in more advanced stages , it was found that the eggs gradually continue to 

 increase in size as they mature, and that as fast as they become detached from the membrane they 

 pass down through the channels to the opening, and are excluded from the body, either at the 

 will of the parent or by internal pressure caused by the increasing size of the eggs, to make room 

 for others. It would be impossible for a fish to retain all, or even a small part, of its eggs in the 

 roe-bags until the last had matured, for the increase during the development is very great, and 

 they would come to have a bulk greater than the entire stomach cavity of the fish. The pro- 

 ducts of the ovaries of a seventy-five pound fi>h, after impregnation, would weigh about forty-five 

 pounds and measure nearly seven gallons, equal to over half of either the weight or bulk of the fish. 



"Another proof that the Codfish deposits its eggs gradually during a long period is seen in the 

 fact that few can be taken from the fish at a time. In ' stripping the fish,' at the hatchery in 

 Gloucester, it was found that only one quart, or less than 400,000 eggs, could be taken from a 

 twenty-one pound fish at a single stripping. Allowing the ovaries of this fish to contain 2,700,000 

 eggs, and the time of spawning to be two months, the fish must deposit in the natural way 337,500, 

 or nearly a quart, each week. 



"But by the artificial method, where strong external pressure is applied, many more eggs are 

 probably secured at once than would be naturally thrown by the fish. Thus the fish must either 

 gradually deposit more or less eggs each day, during the entire spawning season, or it must deposit 

 at intervals separated by only a day or two at most. 



"The schools of Cod move about but little during the spawning season, except when driven 

 away by enemies or by violent storms. After they reach the waters of Cape Ann, fishing continues 

 best in the same localities, and even upon the same spots, until they leave. The individuals, too, 

 seem to move about but little among themselves. When the female becomes ripe she remains 

 quietly near the bottom, while the male, a little more active, often swims higher up. This is indi- 

 cated by the fact that greater numbers of spawning females are taken with the trawl, which 

 lies directly on the bottom, than with the hand-line a little way above it, while the males are taken 

 on one as readily as on the other. 



"It may not be impossible that the eggs are fertilized while floating about in the water some 

 minutes after exclusion, and that the strong tides usually found on the spawning grounds play an 

 important part in distributing the germs, thus making the chances of impregnation more favorable. 

 Indeed it may be possible, and, if the spawning goes on gradually for several months, seems not 

 improbable, that the immediate presence of the opposite sexes during the act of spawning is not 

 necessary, but rather that the eggs are fertilized mainly by accidental contact. Observations 

 would seem to strengthen the probabilities of this theory; for, if the fish went in pairs, they would 

 often be taken on adjoining hooks of the trawl, or one on either hook of the hand-line. Such is 

 not usually the case, however, but, on the contrary, several of the same sex are more frequently 

 taken together. 



"The eggs have a specific gravity of 1.020 to 1.025, as indicated by the fact that they float iu 

 salt water and sink rapidly in fresh. They may be found at the surface in common with eggs of 

 the Pollock, Haddock, and probably other species of the cod family, when the sea is smooth; but 

 when the water becomes rough they are carried to a depth of several fathoms by the current, 

 though the tendency is to remain near the surface. The oldest fishermen had not the slightest 

 knowledge of this fact, but held to the theory that the females deposited their eggs on the rocks, 



