THE SALMON 187 
period. It is generally supposed that they return to the fresh 
water about a year after they have left it, and this is probably 
The Grilse true of the majority. They are now adult, but virgin, 
stage salmon, retaining some traces of adolescence and 
showing a considerable variation in size. Having left the river 
weighing but two or three ounces each, grilse begin to reappear 
in fresh water during May, presumably of the next year, weighing 
from 2 |b. to 5 lb. As the summer and autumn months pass, 
grilse continue to run, increasing in size as the season advances, 
being taken as heavy as ro lb. and even 12 |b. It is possible 
that these heavy grilse may have remained two whole seasons in 
the sea before revisiting the river where they were hatched. 
Their approach to maturity and the rate of development of the 
ovaries in females* probably depends upon the amount of food 
which they find in the sea, This was formerly considered 
to consist entirely of crustaceans—shrimps, prawns, and the 
like—and to such diet was attributed the beautiful and peculiar 
hue, the ‘salmon colour”’ of the flesh of this fish ; but recent 
observations have shown conclusively that salmon subsist 
chiefly upon herrings, haddocks, and other pelagic fish. In the 
spring of 1899 Dr. Kingston Barton, on opening a salmon taken 
at sea, found in the stomach no fewer than six large herrings, 
“that nearest the salmon’s mouth being barely changed in 
appearance, while the sixth had only the spinal column 
undigested, those in between being in a graduated state of 
digestion, and yet all these fish were in the one cavity.”+ In 
other words, this salmon had swallowed consecutively more 
than any ordinary human being could attempt at a single meal ! 
The intestines, also, were very full of fecal matter, showing 
that this was no exceptional indulgence. Dr. Barton adds a 
note of the surprising fact that both in salmon and sea-trout 
the food-fish is always swallowed tail first. 
* Milt capable of fertilising ova is often developed in male parr before 
they go to sea. 
t Journal of Anatomy and Physiology, April, 1900, p. 297. 
