77 
period. The produce each year thus varies greatly in size, and 
during growth they are to some extent unequally affected by the 
successive seasons of acceleration and retardation. The various 
regions in which plaice occur are not equal either with regard to 
temperature and food. The variations in the seasons also leave 
more or less an impress on growth. 
The most important recent work on the subject has been done 
by Fulton and by Apstein, and notwithstanding that the research 
was made in the one case on Scotch plaice, and in the other on the 
plaice of the Baltic, the conclusions are very much in accord. 
During the last six years I have carefully measured the fish 
caught in the first haul at our trawling experiments, and in my last 
report I brought together the results so far as they related to the 
growth of the plaice. The experiment in migration now under 
consideration serves to confirm the determinations arrived at by an 
analysis of the plaice caught by the trawl. I do not propose to 
give now, however, the details in figures, nor the graphic con- 
sideration of these, which have led to the conclusions given in the 
following table ; — 
PLAICE. 
Age. 
Average 
Length. 
Gain. 
Average 
Weight. 
Gain. 
Proportional 
Rate of Growth 
in Weight. 
Years. 
1 
Inches. 
3-9 
Inches. 
Ounces. 
0-4 
Ounces. 
2 
7-9 
4-0 
3 
2-6 
650 
3 
10-8 
2*9 
8 
5 
167 
4 
13 
2-2 
14-5 
6-5 
81 
5 
15 
2 
22*5 
8 
55 
6 
16-8 
1-8 
31-5 
9 
40 
7 
18-4 
1-6 
40 
8-5 
27 
8 
19-4 
1 
47 
7 
18 
9 
20*2 
0-8 
53 
6 
13 
10 
20-8 
0-6 
57 
4 
8 
The earlier stages were determined from a consideration of a 
graphic analysis of the first haul, and of the results of the migra- 
tion experiment.* I have ventured in bringing the results together 
to continue the curve, so as to be able to state approximately the 
* In the 18tli Ann. Rep. of the Liverpool Marine Biol. Comm., p. 37 (1904), it is stated that 
the 4-5 months old plaice kept in tanks were between and 2-in. in length. Only 
three of the 80 measured were over 3-in. long. 
