ITS INFANT STAGE. 207 



even more difficult of investigation than the one treated 

 of in the preceding chapter, namely, its growth. 



I have already stated, in the way of parenthesis, that 

 the parr of Tweed and Teviot, unlike those of the 

 Drumlanrig ponds, descend to the sea in the shape of 

 smolts, in the year following their birth or production. 

 There can be no doubt whatsoever as to this fact. 

 All the parrs of these rivers, with, it may happen, the 

 exception of one or two individuals, descend to the 

 salt water during the smolt season, and in the charac- 

 ter, more or less developed, of smolts. During the 

 latter end of May and a considerable portion of June, 

 the parrs are not to be found in either river, and when 

 they begin to re-appear, which they do in considerable 

 numbers about the commencement of July, they are of 

 a size very insignificant, in many cases, not much larger 

 than a full-grown minnow. They increase in this 

 respect, however, with tolerable rapidity ; as quickly at 

 least as the fresh-water trout they cohabit with, and 

 acquire before October a weight averaging from two to 

 three ounces ; after which, food being scarce, all fur- 

 ther growth for the season becomes suspended. While 

 in the infant state, immediately on their breaking the 

 shell,* immense numbers of them are devoured by sea- 

 gulls, river-trout, &c. I have witnessed, in the lower 

 part of the Mertoun water, a flock of marine birds, not 



* With regard to the hatching of the ova, Mr. Shaw has ascertained 

 that it is completed, when the temperature is 36, in 114 days ; when 

 43, in 101 days ; and when 45, hi 90 days. On the young fish emerg- 

 ing from the external membrane, the remains of the yolk continue 

 attached to them, and are not completely absorbed until the expiration 

 of nearly four weeks, during which period they act in the place of 

 nourishment. At the end of two months the fry attain the length of 

 1 inch ; at the end of four months they measure 2 inches ; and at the 

 end of six months 3 inches. 



