Ill GENERATION OF FISHES AND THEIR FECUNDITY 8 1 



period but only the small quantity required for the first day or 

 first few days, more being produced after the first quantity was 

 shed. 



The comparison of the grey gurnard with the angler with 

 respect to the relations of the sexes and the rate of spawning 

 corresponds to that between the sole and plaice. The gurnard 

 spawns gradually, and although no special observations have 

 been made on the size of the milts there is, according to Dr. 

 Fulton, a very great inferiority on the part of the males in point 

 of number, the females being more than four times as numerous. 

 In the angler, on the contrary, all the eggs are shed simul- 

 taneously, and the males were found to be more abundant 

 than the females in the proportion of lOO to 26. There 

 is, however, an additional reason why in the angler a large 

 quantity of milt should be necessary. The eggs although 

 buoyant do not separate, but remain connected together in a 

 continuous sheet. Owing, therefore, to the diffusion or scatter- 

 ing of the milt in the water there is doubtless a considerable 

 waste of that substance in the process of fertilisation. 



Although the small size of the milts in the slow-spawning 

 fishes, especially in the sole, has attracted most attention, it is 

 also true, as might be expected, that the roes in these species 

 are smaller in the spawning season than in fish which spawn 

 quickly. Ripe eggs being larger than partially developed eggs, the 

 more ripe eggs present at the same time the more enlarged will 

 be the roe. But for the reasons already given the differences are 

 not so extreme as in the case of the male organs. Dr. Fulton has 

 referred to the very different degree of ease with which the eggs 

 are carried in different species. In the plaice, flounder, cod, had- 

 dock, and several others, all producing large numbers of ripe eggs 

 simultaneously, the body is much swollen or distended by the 

 ripe roes in the spawning season, while in the sole, gurnard, 

 and others the enlargement of the belly in the gravid condition 

 is much less striking. Great enlargement or distension of the 

 body of course implies that the ripe roes are larger in proportion 

 to the size of the fish than in the opposite case. The internal 

 organs, especially the stomach and intestines, are necessarily 

 compressed by the enlarged roes, and this is the reason why so 

 many fishes take little or no food during the spawning period. 

 Gravid female cod, for example, are taken in large numbers by 



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