288 THE ZOOLOGIST. 



vein (so-called " heart ") is another feature of interest, and the 

 impulse of the heart causes a slight jerk in it on each contrac- 

 tion. In Shaw's figure in the Trans. Eoy. Soc, Edinburgh, the 

 vitelline vein runs behind instead of in front of the large oil- 

 globules. The vessels of the yolk-sac do not branch very 

 minutely, but enter the venous system by a current two or three 

 discs broad. 



Sooner or later, then, the Salmon leaves the sea and enters 

 the mouths of certain rivers for the purpose of spawning, and so 

 strong is the instinct which impells it, that, using the term 

 Salmon in its widest sense, it sweeps through the whole length 

 of the largest rivers, and, as is well known, reaches Bohemia by 

 the Elbe, Switzerland by the Ehine, and the Cordilleras of 

 America by the Amazon — the course of which is more than 

 2000 miles ; and it has been stated that it reaches the sources 

 of the river in about three months, but this appears to need 

 verification, for Mr. Calderwood lately found that his marked 

 fishes took ten days to cover sixty-eight miles, though of course 

 it is unknown whether a straight course was followed. No 

 country, however, shows on a more gigantic scale the impulse 

 just mentioned than Canada, where the work of Dr. Edward E. 

 Prince, the Dominion Commissioner of Fisheries, has lately 

 thrown a flood of light both in regard to investigation and 

 legislation.* The vast hordes of the various species of Salmon, 

 for instance, which pour round Vancouver Island from the 

 North Pacific to enter the clear, cold waters of the Fraser 

 Eiver, defies computation, and the phenomenon is still more 

 remarkable when it is remembered that the majority in this 

 instance perish after spawning. Even in our own waters the 

 mortality after spawning is considerable. 



In its course up a river to the pure rills and streamlets 

 which form its source, the Salmon encounters many obstacles, 

 such as precipitous falls, cascades and artificial obstructions, 

 some of which can only be passed in high flood, whilst a few are 

 impassable except by salmon-passes, early introduced by Mr. 

 Smith of Deanston, and by Messrs. Ashworth in their Galway 

 fishings. Moreover, it has to run the gauntlet of the endless 



* The extent of these fisheries is well shown by a communication by 

 Prof. Prince to the International Fisheries Congress at Piome in 1911. 



