Translation Series No.1211

•
- 71 -
ovary that has already been mentioned (Fig. 14). The follicle-forming
tufts of this tissue extend deeply into the gonad. Whereas the maturing
oocytes separate easily after treatment with Gilson's solution, the re-
cruitment stock sticks very tightly in the tissue and is often invisible
and thus not amenable to quantitative treatment. Maturing oocytes are sup-
plied plentifully with yolk, whereas.the recruitment stock haà no, or hardly
any yolk. The oocytes of the recruitment stock are, however, of different .
sizes (Fig. 15). The number and the diameter of the oocytes vary greatly
in the different regions of the ovary on account of the varying size of
the discs (Fig. 17). In the discs that are situated in the region of the
greatest circumference of the"gonad, the diameter of the oocytes and their
huMberece greater than in the end discs. The number of maturing oocytes
in 12 . salmon with a total length of between 74 and 79 cm varied from 49
to 205 per disc. The weighted mean was-134.
• It will now be our task to investigate the development of the
oocytes in salmon of different length and of different age and to find an
indication of the probable time of spawning. Hitherto it has been known .
through investigations of the stock that in the spring of every year a
part of the salmori in the sea of sea year class A.2 8 and the majority of
the sea year class A.3 8 emigrate to spawn. Thus one has to take into ac-
count that at least some of these fish have reached a stage in their dev-
elOpment in April that enables theM to spawn in the following fall.
. The synopsis of the results shows that even in such salmon
that have been caught at the saine time there are considerable differences
in the diameter of the oocytes. It was not immediately possible to make .
an unambiguous distinction between salmon with Well-developed gonads,
8 A.2 = two years in the Baltic Sea, A.3 = 3 years in the Baltic Sea (cf. 5.1.).