54 THE LIFE OF THE SALMON 
female grilse bears a much smaller proportion to the 
weight of the body of the fish than is the case in 
female salmon. In this respect grilse differ from 
salmon, both large and small, where the proportion is 
practically constant at 3°02. In grilse it is only 
1°95 during the months named. In terms of 100 
this percentage in grilse and salmon respectively is 
as 64 to 100. As the season advances, the degree 
of development of the genitalia steadily increases, 
but the proportional development is later in the 
grilse than in the salmon, or commences later, 
although both grilse and salmon become fully ripe 
at about the same time. These particulars were 
clearly deduced by Archer * from the observations 
referred to. 
After leaving the river, it is clear that the grilse 
can and does travel to fairly distant points on the 
coast at considerable speed. A Deveron grilse kelt 
marked at the mouth of the river (Duff House) was 
found in a coast net 50 miles distant (Port Errol) 
in 88 days. A similar recapture was made in 109 
days. Another Deveron grilse which had travelled 
70 miles to Cove, south of Aberdeen, in 122 days 
was found on recapture to have gill maggots 
(Lerneopoda salmonea, Linn.) still attached. The 
fish was sent to me in Edinburgh with the mark 
in situ, and I had the maggots carefully diagnosed 
by Mr. Scott, a specialist in the lesser crustacea 
and a naturalist on the staff of the Fishery Board. 
It is as yet uncertain how long those fresh water 
parasites can remain attached to the gills in sea 
* Fourteenth Annual Report Fishery Board for Scotland 
Part IT. p. 9 et seq. 
