24 
THE SPAWNING OF THE COD. 
On March 20tli it was found that the tank in which thre«' 
codling- and a numher of small cole fish were kept, contained 
a large number of floating eggs. These proved to be the 
eggs of the cod. — Average diameter, 1-28 cm. 
The cod were obtained as follows: Two at the trawling- 
experiment in lllyth Bay on January 5th, 1909, and the 
remaining one was caught on the hook off Cullercoats on 
March 3rd, 1910. One of the former died on Julv 17th this 
3 'ear, and was found to be an apparentlj^ immature male 
measuring 19‘T inches (50'2 cm.), and an examination of the 
scales and the otolith showed it to be in its fourth year. 
The other two measured 20‘T and 20'0 inches (52‘7 and 52’5 
cm.) respectivelj' and the scales which were taken from the 
living fish point to their being in their fifth j'ear. It is 
more than probable that these two are male and female, for 
as will appear from what follows onh^ one female spawned. 
This was evidenced bj- the marked periodicitj’ with 
which the spawning occurred. On the day when the eggs 
were first observed thej* were found to contain second, fifth 
and eighth or ninth daj- enibr 3 a:)s, and this puts the begin- 
ning of spawning at about March 11th. Idie larvae began to 
be hatched between the 23rd and the 24th, and this with 
man}' observations made during the period of egg laying 
showed that the interval between egg laying and hatching 
was usually 12 days. The average temperature of the tanks 
during the time was 5'5° C. 
First day eggs were again obtained on the 23rd and on 
the 2Gth and the 29th, which was the last day the cod 
spawned. Thus during a period of about 19 days spawning 
took place at intervals of 3 to 4 days on six occasions. It 
was evident, furthermore, that the spawning took place in 
the early morning. 
A series of figures drawn by Mr. Storrow show the 
advance made from day to day in the development of the 
embryo within the egg. The numbers appended to the 
