178 



2. Experiments on the Growth of the Fry of the Salmon, 

 from the exclusion of the Ova to the age of seven 

 months. By Mr John Shaw, 



The author of this paper had formerly made experiments on the 

 growth of the salmon fry, by procuring spawn from the river bed 

 wiiere it had been deposited by the salmon. Not considering thr 

 experiments, however, as entirely unobjectionable, he procured t 

 fishes from the river Nith in the act of spawning; and having ex- 

 pressed the ova of the female in a convenient place, the milt of the 

 male fish was made to impregnate them as nearly as possible in 

 imitation of the natural process. The ova were then placed in 

 ponds prepared for the purpose, and so arranged as to exclude all 

 chances of error as to the species, or the nature of the progeny. 

 The ponds were two in number; — one twenty-five by eighteen feet, 

 — the other fifty by thirty feet, and two feet deep. The bottom 

 was thickly imbedded with gravel, and a small stream of spring- 

 water entered the ponds at the upper corner, and escaped by 

 openings at the other end. Both apertures were covered with a 

 wire grating. The ova in one experiment were deposited on the 

 20th of January 1837. On the 10th of March (fifty days after de- 

 position), the embryo fish were visible. On the 27th of April 

 (ninety-eight days after deposition), they were excluded from the 

 egg. Specimens were exhibited at thirty days old, taken on 26th 

 May, measuring nearly an inch in length, and the ovum still adhe- 

 rent. On the 27th June, at two months old, the fry measured an 

 inch and a half in length ; and on the 27th of October, at six months 

 old, a specimen exhibited measured about four inches in length. 

 The temperature of the pond and the air was noted at the periods 

 of examination. Another experiment in a diflFerent pond afforded 

 analogous results. Mr Shaw is of opinion, from what he has ob- 

 served in these and former experiments, that the young salmon re- 

 mains in its native stream for two years after being hatched ; and 

 that the parr, or what is termed the parr in his neighbourhood, is 

 the young of the salmon. 



The following Donations were presented : 



Coraptes Rendus Hebdomadaires des Seances de TAcademie des 

 Sciences, (1837 2'"« Semestre), Nos. 20, 21, 22 — JSy the Aca- 

 demy, 



