of the Fishery Board for Scotland. 



117 



April 27. — Vc. — Three live larvae were got. None was found after this 

 date. Some of the eggs contained dead embryos. 



This batch of eggs hatched out after an incubation period of 37 to 52 

 days. In this connection the fry that appeared on April 2nd have been 

 neglected. For the temperature of the water see Vc, Table, p. 118. 



April 16. — Vc 1 . — Some lively fry, 94 in number, were got on this date. 

 The fry were carried away by the overflow and caught in a trap. It was 

 thus possible to separate the fry that hatched out on each date. The trap 



April 17.— 100 live 



„ 18.-75 





„ 19.— 63 



» 



„ 20.-17 



>> 



,. 21.— 19 



?> 



„ 22.-2 



J5 



„ 23.-6 



>) 



„ 24.-1 



)> 



„ 25.-1 



JJ 



„ 26.-2 





„ 28.-1 



» 



„ 29.— 1 dead Is 



On May 1st the spawn was removed. A large quantity of fully-developed 

 larvae was found dead in the box. These had got trapped in the dead water 

 in the bottom of the box. The spawn in this box consisted of large lumps 

 measuring one inch or more in breadth or length, but less in thickness. 

 The eggs on the edge of the lump had hatched ; those inside the 

 lump had died. There was a mould over the pieces. Many of the dead 

 eggs had embryos in them. The eggs inside the lump had developed for 

 some distance, some having reached the closure of the blastopore, although 

 in the centre some had died in the disc stage. The piece does not form a 

 solid mass. There are interstices between the eggs. The eggs inside the 

 mass were quite clean, while the outside was covered with a thick mat of 

 debris, which will in itself tend to prevent the aeration of the inside eggs. 

 Where the temperature was kept low the eggs that died did not succeed in 

 causing the death of all the eggs. It would appear that as the embryo 

 grows in the egg a greater amount of aeration is required, and it is possible 

 that if there had been a system of mechanical aeration the eggs, even inside 

 the lumps, might have developed successfully. 



The eggs in this batch remained in the egg over a period of from 41 to 53 

 days. For the temperature of the water during this time, see Vc 1 , Table, 

 p. 118. 



[Table. 



