126 



Part III. — Twenty-seventh Annual Report 



development no longer took place. This temperature was for Phuronectes 

 platessa, -2*4° C. Vide also Apstein.* 



Temperature of the Cooled Water in which the Eggs of the Haddock 

 and Plaice were kept. Degrees centigrade. 



Date. 



M. 



m. 



Date. 



M. 



m. 



Date. 



M. 



m. 



Apr. 23 



3 



2-6 



May 



8 



2*3 



0 



May 



23 



5 



0 



» 24 



2-6 



1 





9 



2-3 



0 





24 



2-8 



0 



„ 25 



2-4 



•6 



5> 



10 



2-2 







25 



3-9 



0 



„ 26 



5-6 



0 



?> 



11 



6-7 



6 



?> 



26 



3-9 



0 



97 



o 4 



0 



J) 



12 



O.Q 



A 

 U 



55 



27 



4 0 



n 

 u 



■ „ 28 



4 



•6 



»> 



13 



1-7 



0 



55 



28 



3-4 



0 



29 



4-5 



0 



>? 



14 



2-3 



0 



)> 



29 



3-4 



0 



„ 30 



4-8 



-•6 



>) 



15 



1-7 



0 



>5 



30 



3-4 



0 



May 1 



45 



0 



') 



16 



3-8 



0 



55 



31 



3-4 



0 



„ 2 



2-8 



0 



)> 



17 



34 



0 



June 



1 



5-6 



0 



3 





•6 



)» 



18 



3-4 



0 



>> 



2 



5 



0 



4 



4-5 



-•6 



>» 



19 



9-5 



•5 



55 



3 



5 



0 



„ 5 



5-6 



0 



>; 



20 



3 



•4 



55 



4 



5-6 



•6 



}f 6 



2-8 



0 



?> 



21 



•6 



•2 



55 



5 



5 



1-2 



» 7 



2-8 



0 



> ) 



22 



5 



1 



55 



6 



3-9 



1-2 



Dannevigt kept the eggs of the haddock in still water, refreshed daily, at 

 a temperature of — 1°C. for 35 days. They were then transferred to water 

 of 6°C., in which they hatched in about two and a half days. He concluded 

 that the development of fish eggs takes place at temperatures below zero, 

 when the specific gravity of the water is sufficiently high to prevent it from 

 freezing. Sea-water of a specific gravity of 1027 freezes at about — 2°C. 

 Dannevig transferred some haddock fry from the water of 6°C. in which 

 they were hatched, some directly into water of 0°C, others into water of 

 10°C, without their apparently suffering. Immediately after transference 

 they appeared quiet and inactive, but they soon again showed their usual 

 activity and vigour. It occasionally happened that eggs kept in water of 

 the low temperature of — 2°C. became inclosed in lumps of ice that floated 

 at the surface. When these melted, while the bottle remained quiet a 

 layer of fresh water was found floating on the top of the sea- water. All 

 the eggs were then seen floating exactly at the same level — at the limit 

 between the fresh and the sea-water. The eggs of the plaice and haddock 

 appeared to be most capable of resisting these changes. The eggs of whiting 

 gradually succumbed : the eggs of the cod were, as a rule, the least hardy 

 amongst them all. 



Experiments on Turbot (Bothus maximus, Will ) 



Two turbot measuring respectively 6| inches and 9£ inches in length 

 were kept for a short time in June in cooled water. They were put into a 

 tin box measuring 18 inches in length by lOf inches in breadth by 8^ 



* " Die Bestimmung des Alters pelagisch lebender Fischeie." Mitteil d. deutschen 

 Seejischerei-Vereins. Nv. 12. 1909. 



t Dannevig — " The Influence of Temperature on the Development of the Eggs of 

 Fishes." Thirteenth Annual Report of the Fishery Board for Scotland for 1894. 

 Part III. Edinburgh, 1895, p. J 47. 



