34 Transactions. 
a good deal here. It was found that in cold weather fish were 
later in spawning than in mild weather ; that during a hard frost 
they spawned very tardily ; and when there was a mild rain and 
rapid thaw, they spawned more freely than under any other 
circumstances. If it were taken from ice-cold water and placed 
in a tank in-doors, the inflowing stream of which was gradually 
warmed, a fish from which it had been found impossible to take 
ova would then yield its eggs freely. Some time ago, when 
seeking salmon ova in the Nith, I could find no ripe fish; but I 
was told by some fishermen that there were plenty to be got in the 
Cluden, which I found to be the case. I instituted some experi- 
ments, in which Mr Rutherford of Jardington and some others 
kindly helped me. We had thermometers placed in the two 
streams ; and found, as I expected, that the temperature of the 
Cluden was higher than that of the Nith. It has been said that 
the temperature of the sea being colder than that of the rivers, 
the fish left it seeking a higher temperature. I have not noticed 
this so much myself; but it is the experience of some writers, 
and is recorded in the Government fishery reports and elsewhere. 
But this I know, that the temperature of the sea during the late 
spring months and in summer was often a great deal higher than 
the temperature of the water in the river, very often varying ten 
degrees or more; and we found—a thing which had puzzled 
naturalists—that salmon leave the sea and run up the rivers at 
all times of the year, more or less. Why should fish run up the 
rivers during the summer months, when the spawning season was 
so far distant? Seeing what an effect temperature had upon the 
spawning of fish, I suggest that its effect on the reproductive 
organs might compel them to leave the warmer waters of the sea 
and take refuge in the rivers. Of course these were the best fish 
—what we call the clean run fish. When the water of the sea 
was of a low temperature, as in early spring, we did not get such 
a large run of fish as we did later on. In the month of March, 
for example, when the east winds are blowing, the fish do not run 
so well as in April; and they don’t run so well in April as in 
May. When I was at Douglas Hall I noticed this particularly. 
So much was it the case that the tacksmen did not find it 
remunerative to put on the net for a month after the opening of 
the legal fishing season. But later on, when the sea got warmer, 
they found a good many fish running. If the weather remained 
cold, and the temperature of the sea at a low point, there was not 
