DEVELOPMENT AND GROWTH OF SALMON-FKY. 5(J1 



desire to effect their escape, by scouring all over the ponds, leaping and sporting, 

 and altogether displaying a vastly increased degree of activity. 



No. 10 is a specimen twenty months old, taken from pond No. 3, on the 5th 

 January 1839. It measures 6 inches in length, and still displays all the charac- 

 teristic markings of the parr. 



No. 11 is a specimen two years old, also taken from pond No. 3, on the 24th 

 May 1839. After assuming the migratory dress, it measures about fci^ inches in 

 length, being about the average size of the brood. I have elsewhere stated that 

 " the circumstances attending the developnaent and growth of the brood in pond 

 No. 3, so exactly correspond with those of the preceding brood in pond No. 1, 

 that then* history would only be a repetition of the former. I may, however, 

 state, that the individuals in pond No. 3 are considerably larger than those in 

 pond No. 1, the difference, at the age of six months, amounting to an inch."* This 

 superiority in point of size, for the first six months, of those in pond No. 3, over 

 those reared in pond No. 1, was not, however, maintained, with the exception of 

 two individuals, much beyond the fii'st six months, as by the period at which they 

 assumed the migratory dress (two years), no difference existed in regard either 

 to size or condition. 



In order to be more distinctly understood regarding the specimen next in 

 order (No. 12), the history of which is most interesting, and highly important in 

 establishing the identity of the parr and salmon, it will be necessary here to re- 

 cur to a passage in my former communication on this subject, where I stated 

 that " pond No. 2, was occupied by a brood of j'^oung salmon also produced by 

 artificial impregnation, the history of which should form the subject of another 

 paper, after I had an opportunity of verifying the experiment by repetition."! I 

 have now repeatedly verified the experiment alluded to, and take this opportu- 

 nity of giving pubUcity to the very extraordinary nature of the results. 



The circumstance of the male paiTs with the milt matured, and flowing in 

 profusion from their bodies, being at all times found in company with the adult 

 female salmon while depositing her spawn in the river, and the female paiTS being 

 in every instance absent, suggested the idea that the males were probably present 

 with the female salmon at such seasons for a sexual purpose. And to demonstrate 

 the fact, I, in January 1837, took a female salmon weighing ] 4 lb. from the spawning 

 bed, from whence I also took a male parr weighing 1^ oz., with the milt of wliich I 

 impregnated a quantity of her ova, and placed it in the stream E, pond No. 2 

 (See Plate XXI), where, to my great astonishment, the process succeeded in every 

 respect as it had done with that which had been impregnated by the adult male 

 salmon, and exhibited, from the first visible appearance of the embryo fish up to 

 then- assuming the migratory dress, the utmost health and vigom-. The very ex- 



* Edinburgh New Phil. Journ. for January 1838 (vol. xxiv. p. 172, note). 

 t Ibid, same page. 



