THE NEW ART OF BREEDING FISH;. 151 



which was not the case when I visited them on the 

 previous day. The temperature of the stream was 

 then 44 degrees. The ova, which for some time 

 previous to being hatched, had been almost daily in 

 my hand for inspection, did not appear to suffer at 

 all from being handled. When I had occasion to 

 inspect the ovum, I placed it in the hollow of my 

 hand, covered with a few drops of water, where it 

 frequently remained a considerable time without 

 suffering any apparent injury. The embryo, how- 

 ever, while in this situation, showed an increased 

 degree of activity by repeatedly turning itself in the 

 egg, an action probably produced by the increase of 

 temperature arising 'from the warmth of the hand." 



Mr. Shaw did not breed artificially for the im- 

 mediate purpose of stocking the river Nith, but to 

 ascertain the growth of salmon-fry ab ovo. Having 

 proved that salmon could be bred artificially, he was 

 satisfied with two alleged main results, viz., that 

 salmon-fry, with transverse bar marks, are identical 

 with the " parr," and that they do not attain the 

 ■smolt, or migratory state, until the age of two years. 

 These results have been disputed by subsequent ex- 

 perimentalists, more particularly by Mr. Young, of 

 Invershin, who maintains that "parr" are adult 

 trout of the smallest variety, and that young salmon 

 (smolts) migrate at the first year, or nearly so, of 

 their age. I am inclined to think that the tem- 

 perature of the water may hasten or retard the 

 period of migration, but not for so long a period as 



