110 



Part HI. — Twenty-seventh Annual Report 



egg is seen whirling round. This is due to the larva having managed to 

 push its tail out. 



March 30, 31, April 1. — IV. and IVb. — Some more larvse were got. 

 April 3. — A few of the eggs of IV. were alive and unhatched, but the 

 great mass of the unhatched eggs are dead and covered with fungus. 

 April 5. — One live larva was obtained from IV. 



April 8. — No fry had been obtained from IV. since April 5. There 

 was a considerable quantity of dead unhatched eggs, and the plates were 

 covered with fungus. The plates were cleared away. 



The first fry had hatched after 23 days, the last after 35 days. The 

 temperature of the water during this period is given in the following 

 Table :— 



The Temperatures of the Water in which the uncooled Lots IV. 

 and IVb. were kept. Degrees centigrade. 



Date. 



IV. and IVb. 



Date. 



IV. an 



d IVb. 



*M. 



f m. 



m; 



m. 











Fe. 





Feb. 29 



tF.3 



2-8 



Mar. 19 



5 



3-8 



Mar. 1 



3-6 



3 



„ 20 



4-8 



4-1 



m 2 



3-6 



3-4 



„ 21 



5 



4-2 



„ 3 



4-2 



3-6 



u 22 



5-4 



4-2 



„ 4 



4-6 



3-8 



„ 23 



§/6-4 



5 



„ 5 



4-6 



3-8 



>, 24 



/6 



5-4 



6 



4-6 



4.4 



n 25 





5-3 



„ 7 



4.4 



4-2 



„ 26 



f5'4: 



44 



» 8 



4-6 



3-5 



„ 27 



/5-8 



5-2 



„ 9 



5-2 



4-2 



„ 28 



f&-8 



5-4 



,, io 



5-2 



5 



„ 29 



65 



5-5 



.. 11 



5-2 



4-2 



>, 30 



/5-4 



5 



12 



5 



4-6 



„ 31 



/5-6 



4-6 



n I 3 



5 



4 



April 1 



fb-6 



4.4 



» 14 



5-2 



4.4 



„ 2 



64 



54 



.. 15 



5 



3-9 



», 3 



6-4 



5-6 



„ 16 



5 



4-6 



4 



61 



5-6 



„ 17 



5 



4-3 



n 5 



/6 



5-4 



„ 18 



4-8 



4-2 









* Maximum of three to seven readings daily (day and night), 

 t Minimum ,, ,, ,, ,, ,, 



X F. — Date of fertilization. §Date upon which fry ("/") was obtained. 



The Cooled Eggs of the Fourth Lot of Spaivn—IYc, IVc 1 , IVc 2 . 



Of this lot of spawn three batches were cooled independently. One, IVc, 

 was cooled from the time of its arrival at Aberdeen. The second, IVc 1 , was 

 put into cooled water on March 7, after it had been a week in the 

 ordinary hatchery water. On this date the eggs were at the stage when the 

 blastopore is just closing (figs. 5 and 6). The third batch, IVc 2 , was shifted 

 into cooled water on March 18, when the tail of the embryo reached round 

 to the neck. Of. fig. 11. 



