126 TRANSACTIONS LIVEKPOOL BIOLOGICAL SOCIETY. 



spawn was obtained, and I should remove from Mr. 

 Fryer's table, at the foot of p. 39, the three columns 

 headed " penned up," as giving no additional useful 

 information. 



It is also unfair to compare an average obtained by 

 including all the fish penned up, many of which did not 

 breed, with the total number of ova calculated as being 

 present in one selected large breeder. The comparison 

 can only be fairly made with the eggs in a similar number 

 of Cod, of the same size as those in captivity, chosen at 

 random from the sea. Even in that case the comparison 

 would only indicate whether there was a diminution in 

 the amount of spawn produced per captive fish. There 

 probably is such a diminution ; but, on the other hand, it 

 is certain that a large number of possible spawners in the 

 sea are killed by man and other enemies before or during 

 the spawning season. 



Then, again, in making a further comparison between 

 artificial hatching and the "processes of nature," it is not 

 right to substitute (p. 41) the number of eggs calculated 

 to be present in the body of a parent for the actual 

 number of eggs treated in the hatchery. This method of 

 " counting the chickens " not only before they are hatched 

 but even before the eggs are laid, is an ingenious method 

 of making the proportion of fry produced in the hatchery 

 seem very small ; but I think the Superintendent's figure, 

 546 per cent, of fry to ova, will commend itself to most 

 people as the correct calculation on the common-sense 

 basis of so many ova supplied and so many fry produced. 

 "What would have happened to, say, 100 of the hatchery 

 spawners if they had been left in the sea, no one can say. 

 How many of them would live to spawn and how much 

 spawn they would produce we do not know. The per- 

 centage of fry to parent fish in the hatchery may, under 



