I^ATURAL HISTORY OF THE SALMON. 69 



Then, as has been done with the salmon and grilse 

 columns, take the latter portion of the year : in August, 

 as compared with July, the trouts fall off nearly 40 per 

 cent, and in September decrease by other 20 per cent. ; 

 which shows, as in the case of the grilse, that the run of 

 young fish is slackening. It is true that in October the 

 number of trouts again increases, but that arises chiefly 

 from the well-known fact that in that month, and later, 

 comes the great rush of trouts seeking to spawn ; and, 

 even if this were not notorious, the fact that these late 

 comers axe adult fish, is indicated by the average weight 

 and size being much greater then than in any month 

 preceding. Is there any producible explanation why the 

 supply of trouts, extending more or less over the whole 

 year, should so suddenly increase for a short time in 

 summer, but the hypothesis that at that time we are 

 getting the fish which are only on their first ascent, along 

 with those which are on their second, third, or fourth ? 

 And do not the facts, that we see a similar, but greater 

 and more sudden increase and decrease in the grilse, and 

 do not see such indications in the salmon column, supply, 

 to say the least, a, very strong presumption that in the 

 trout column you have both young and old, in the 

 grilse column only young, and in the salmon only 

 old fish ? 



In order to put our best foot foremost, we have not 

 adhered to logical sequence, and now adduce a fact 

 which properly should have come first in order : the 

 fact that salmon and grilse are always found together— 

 i.e., that where there are no salmon there are no grilse, 

 and where there are salmon there are grilse, and vice 



