— 172 — 
He found that the fish after their first period of growth (i. e. when one year old) meas- 
ured 5—7 cm., after the second (at two years of age), 8%—111%. All were then imma- 
ture. At the end of the third period, being then three years old, some of the fish are 11— 
13 em. long, and still immature, while others have a length of 13—14cm., and have arrived 
at maturity. The attainment of maturity can thus be placed at somewhat over the 
o 1% 9 10 15 : 20 
fe — — — 
dunt 1908 
Juli 
Ququst 
Januar 1909 
Februar 
Mars 
[Septem b. 
Oct ober 
Novemb. 
Decemb. 
Januar 1910 
[Februar | 
it 
Fig. 103. Amount of fat in sprat. 
—-— greatest average =: -- smallest (Butt). 
third year, and at a length of about 13cm. This agrees with Burr’s analyses, which 
show the amount of fat as increasing with size up to a length of 11 or 12 em., after which 
it commences to decrease. 
Variations in the composition in point of age and size of the sprat. 
In the course of the sprat investigations it was noticed that the composition in point 
of size exhibited considerable fluctuations during the years 1908—1910. Butt gives 
(I. c.) a table showing the composition in this respect, indicating the average percentage 
in weight for each cm. group in each of the years 1908—1910. The averages are based 
on 74 different samples. 
