82 SALMONID^ OF BRITAIN. 



The period salmon eggs take incubating is subject to considerable variation (see 

 p. 35 ante), thus it has been found that at 45°'F:ihr. they take 90 days, at 43° 

 101 days (Shaw), at 41° 97 days (J. Maitland) and at 3G° 114 days (Shaw), 

 while their normal period of hatching has been deferred to the 148th day by 

 placing them in ice vaults (see p. 43 ante) ; but freezing them is probably 

 fatal (see p. 37). Mr. Bartlett, Proceedings of the Zoological Society, 1859, p. 125, 

 observed how some of these eggs under his supervision at the Crystal Palace were 

 taken on February 5th and deposited in boxes with gravel and water which 

 averaged 57" Fahr., and the young hatched on March 7th, or in thirty days. 



But salmon eggs, even in redds,* are not permitted to rest in peace and hatch 

 in security : they have many accidents to escape from and numerous enemies whose 

 vigilance must be evaded, and which have been already enumerated (p. 28). 



When these little fish emerge from the eggs as alevins (see p. 43), they have a 

 large bag (the umbilical sac) attached to their under surface a little behind the 

 gill-opening ; this contains the noui-ishmeut which is to serve them from three 

 weeks to two months for their subsistence, and they do not commonly take in 

 much food by the mouth until it is absorbed. Weighed down by it they lie quietly 

 among the stones at the bottom of the stream and seek concealment from fish 

 larger than themselves, water insects, and other enemies which now commence to 

 feed on them. Living in shallows many forms of large fish are unable to follow 

 them, but floods may carry them down to their enemies. At about the end of 

 two months the alevins are a1)out Ij inches long, at four months 2h inches, and at 

 six months Of inches ; but there are great individual variations in size among 

 them. The yelk or umbilical sac in young salmon is generally of a much more 

 orange colour than is seen in the alevins of fresh-water trout. Monstrosities are 

 not rare, and being similar to those occurring among trout they will be alluded 

 to together. 



The alovin stage, or that which begins when the fry is first hatched, passes after a 

 few months into that of a par or pink, when the fish becomes adorned with brilliant 

 colours, ashas been already described. Theseyoung fish i-eside two years in our rivers 

 migrating seawards in their second or third spring, and occasionally iu the autumn 

 as smelts. Many discussions have arisen as to whether the par is or is not the 

 young of the salmon, or even a hybrid between it and the trout, and though there 

 exists a strong family resemblance between the .young of the salmon and treat, 

 still it has been abandantly proved that the Salmo salar passes through a par 

 stage. In fact it was long ago pointed out that in rivers destitute of salmon 

 there were no pars, while wherever they existed there pars were present. This 

 point has now been most conclusively decided by hatching out eggs and milt taken 

 directly from salmon and artificially rearing the progeny, the result being pars. 

 It has also been shown that similar pars can be raised from the eggs of smolts 

 fertilized from pars, or salmon similarly fecundated, from grilse and salmon, from 

 pure grilse, and from pure salmon. 



Whenever one attempted to come too near the female he made a rush at him, seized him and 

 shook him as a retriever would shake a hare. This game was carried on for a considerable time, 

 until every one was more or less torn to such an extent that in a few days several of them were 

 found lying dead on the bank, and I had no trouble in identifying them as those engaged in the 

 combats." 



* Mr. Brander examined a redd that appeared to have been left dry, but on opening it found 

 that a little water was trickling through the stones and gravel, which was sufficient to keep the 

 ova healthy. Having scraped a hole, he obtained a considerable number of eggs, and these he 

 transferred to a pail of water, where two-thirds hatolied within periods varying from five minutes 

 to twenty-four hours. About a week subsequently he returned to the same spot, and had another 

 dig for salmon eggs (no rise having occurred in the river during the interval). He collected more, 

 and putting them into the water, they hatched as the former ones had done. He advanced that 

 this may be a provision to prevent ova deposited iu localities where the depth of the stream is 

 Hable to considerable fluctuations, from becoming lost or killed, as must occur unless a delay, to 

 obtain suitable time, could be provided for. But there are no means of knowing whether these 

 ova were all deposited at the same time. While at p. 38 ante, will be found the account of 

 experiments made at Cheltenham with eggs in artificial redds, and although they were kept 

 several hours daily uncovered by water they hatched on the same day as others which were 

 kept all the time with a stream flowing over them. 



