of the Fishery Board for Scotland. 



107 



So far as this research bears evidence on the question, I shall take as 

 the normal relation of a to x> that given by the eggs of the cod. The 

 spawning season of this form lasts from March to June, and during the 

 four months the ratios are 1*5, *74 ; -74, and *66 respectively. The ratios 

 deduced from Hensen and Apstein's Table for the eggs of the cod are 

 considerably smaller. For their second trip, which took place in the 

 beginning of March, the ratio was *6, and for their third trip, at the 

 end of April, the ratio was then - 4. In the middle of February 

 the ratio was "8. In this case also, as the German authors point out, the 

 proportion of early eggs is greater in the beginning of the spawning 

 season, and diminishes towards the end of the season. The ratios which 

 I found to exist in the case of the eggs of the cod differ to some extent 

 from those given by the sum of the eggs of all species ; but the latter are 

 not, owing to their referring to a mixture of eggs of species having 

 different spawning seasons, likely to be identical with the true ratios of any 

 one species. The experiments in Loch Fyne were carried out once a 

 month ; but in order to accurately determine the normal relations between 

 the number of eggs of each stage at different periods, continuous observa- 

 tion in a spawning area during the whole spawning season would be 

 necessary. Weekly examination would be required in order to eliminate 

 any irregularity or intermittence in spawning to which through meteoro- 

 logical or other conditions the whole body of spawning fish may be 

 subject. Hensen and Apstein also point out how the disparity between 

 the numbers of early and further advanced eggs may be due (1) to the 

 fact that the eggs in Stage e (about ready to hatch) may sink to a greater 

 depth than the early eggs ; (2) to the destruction of the eggs in one way 

 or another. From a consideration of the results of their North Sea 

 expedition they are led to the conclusion that a very large percentage 

 of the eggs die ; and that for every 100 eggs found in the water, 159 have 

 been spawned and fertilised. And, further, of 100 eggs 35*9 only hatch. 

 So far as my own observations in Loch Fyne go, I am unable to 

 corroborate this estimate. On their second and third trips the German 

 authors found, in certain collections consisting of 2600 eggs, 125 eggs of the 

 fifth stage (e), i.e., one-twentieth of the whole. In Loch Fyne I obtained 

 during the months of March, April, and May 6113 eggs, and of these 

 529, or one-eleventh, were in the fifth stage. On Station II., however, 

 in April, of 887 cod eggs 332 were in the fifth stage, the remaiuing eggs 

 being arranged as follows : — Stage a, 157 ; 67 ; y, 201 ; 8, 130. 



It is also necessary to remember the difference between a confined loch, 

 like Loch Fyne, and the open sea. It is possible that many of the 

 cod eggs collected in Loch Fyne were drifted in from the outside during 

 their development, and this might increase the proportion of those found 

 to be in late stages. 



As to the suggestion that the eggs in advanced development sink, 

 Hensen and Apstein {o.e., p. 62) write regarding cod eggs : — " In 5 

 " vertical hauls, 22 eggs of the fifth stage were found at depths greater 

 " than 20 metres [10 fathoms], and only one at a depth less than 5 metres 

 " [2 h fathoms]. In 9 horizontal tows [surface], which produced 828 eggs, 

 "only 15 eggs belonged to the fifth stage. The eggs in the last stage of 

 " development then seek greater depths. They sink to regions which are 

 "comparatively poor in living organisms, and where the darkness affords 

 " them safe shelter." 



My own records do not refer to a greater depth than 15 fathoms (27 

 metres). Only in rare cases were cod eggs of the fifth stage found deeper 

 than 6 fathoms. The great majority was captured at depths less than 

 G fathoms. I give here an analysis of all the eggs obtained on 



H 



