WHICH HAVE NEVEE DESCENDED TO THE SEA. 449 



ts original habits as a smolt. But after first descending to the ocean and tasting its 

 murine food, it never again resorts to its infantile food as a constant mode of nourishment. 

 He further says, "The absence of this [marine] kind of food forms an insurmountable 

 obstacle to the preservation of Salmon and of some kinds of Sea-Trout in freshwater lakes." 

 It has been suggested that a sojourn in fresh water, even should such be only temporary, 

 may o-ive the first impetus towards the seasonal development of the sexual organs. 



Shaw remarked that solitary instances have occurred of large female parrs having been 

 found in Salmon rivers with the roe considerably developed, and he ascertained that by 

 detaining the female smolt in fresh water until the end of the third winter, indi- 

 viduals are found in this comparatively mature condition. Davy* says :-" I have 

 examined hundreds of parrs .... Male parrs I have frequently found with mature milt, 

 but never a female with roe correspondingly developed ; on the contrary, in the female 

 fish without exception, the ovaries have been so small, tbat had they not been sought 

 after carefully they would have escaped notice." Russel t asks of Mr. Young, « Did he 

 ever see a female parr with a developed roe ? He never did and never will " $ 



In this search for roe developed in young Salmon that have not descended to the sea 

 experiments would appear to have ceased in this country; but after an interval o 

 about 45 years it was intended to carry them on at Howietoun. Still as it would 

 not be improbable that some objection would be raised to young fish for this purpose 

 being removed from rivers to ponds, it was determined to rear the parr from the eggs and 

 see if smolts or grilse when thus raised in suitable ponds and properly cared for would or 

 would not breed in fresh waters. 



Brown § observed that " no female parr has yet been discovered with roe developed. 

 This I think, must be taken to read that no young female Salmon in the parr livery that 

 has not been to the sea had been discovered with ova fully developed. For as I shaU 

 presently endeavour to show, parr or rather smolt with well-marked parr-bands have given 

 ally developed ova at Howietoun. Brown || determined to endeavour to rear the ova up 

 to the smolt stage, and obtained certain ponds, into one of which the sea ebbed and flowed 

 at Stonehaven in Kincardineshire. They consisted of two ponds, a freshwater one 40 X 20 

 yards and a saltwater one 60 x 30 yards. The distance between the ponds was about 

 30 yards with a fall of eight feet. An iron pipe 18 inches in diameter communicated 

 with the sea. Spawning fish were put into the freshwater pond and afterwards made 

 their way to the sea-pond, but unfortunately poachers destroyed the experiment, which 



was not renewed. , .. . „, . 



Clean Salmon having only a thread of milt or roe in them are found m Salmon rivers 

 during December, January, and February. These would seem to be temporarily sterile f 

 became ova and milt may be detected by means of the microscope^ Mr P I Well 

 .ave evidence that these fish do not spawn until the November or December following, 

 ° * . Transactions of the Royal Society of Edinburgh • (Dec. 1854), vol. xxi p. 253 t < The Salmon,' 1804, p. 30. 

 ♦ Tarrell is said to have adduced two instances of parr containing ova m the month of March. 

 + , i -looo on 'I Op. tit. p. lib, 



8 < Sfcormontfield Experiments,' 1862, p. 89. 1 , , !«.*«,- * -r* 



f Siebold has found that certain individuals are not sexually developed; and he supposed that th,s sen. ty 

 extended throughout their existence. Widegren and others have opposed tins v.ew, centering that such sterility 

 is temporary, merely affecting a few individuals. 



