290 THE ZOOLOGIST. 



late Salmon-rivers, as they were called, owed this feature to the 

 temperature of their waters. Thus, in Britain, certain rivers 

 arising from lochs are earlier than some which do not ; Yarrell, 

 for instance, quoting Sir William Jardine's case of the Oikel and 

 the Shin in Sutherlandshire. The Oikel springs form a small 

 alpine lake about half a mile in breadth, whereas the Shin, a 

 tributary of the Oikel, takes its origin from Loch Shin, a large 

 and deep loch connected to a chain of other deep lochs. Early 

 in spring all Salmon entering the common estuary diverge up 

 the Shin, and do not pass into the Oikel until later. 



The eggs in the ovaries of the Salmon are developed so as 

 to form a mass of several pounds, varying according to the size 

 of the fish, on each side by the utilization of the nutriment 

 stored up in the muscular and other tissues, as indeed had long 

 been suspected, but more clearly demonstrated by Meischer 

 Euesch and Noel Paton.* 



In the ovary, as in that of the Wolf-Fish (Anarrhichas), the 

 eggs attain a comparatively large size, and, moreover, all reach 

 maturity about the same time, so that they are shed within a 

 limited period — a condition very different, for instance, from 

 that in the Cod or Haddock. On entering a river some pass 

 upward to the spawning-ground with considerable rapidity, 

 whilst others, especially in the larger rivers, or in those with 

 lakes, may remain many months before spawning, and their 

 perseverance in overcoming natural obstacles in their ascent to 

 suitable spawning-grounds is well known. Fishes are usually 

 credited with small intelligence, but as a matter of fact their 

 intelligence is keen. Both intelligence and instinct, and in 

 some cases memory, come into play in the selection of a good 

 spawning-bed of clean gravel— as at the Boat (now the Bridge) 

 of Caputh. Few sights are more interesting to the naturalist 

 than to watch the fishes swarming on such a spawning-bed in 

 November. The quiet stretch of shallow water (for it is out of 

 the main current) is alive with the dorsal fins of the males as 



* It may be noted that before Dr. (now Professor) Noel Paton began 

 his researches the late Mr. James Johnston, of Montrose, my colleague on 

 the Fishery Board, agreed to present two Salmon per week for this purpose, 

 and he loyally carried out his promise. Mr. Johnston deserves grateful 

 remembrance for his generosity. 



