1g70.1, :,° IN THE GROWTH OF SALMON, 31 
remainder of the ova left in charge of the correspondent to receive 
widely different treatment—hatching to be carried on in the open 
air, and the tiny fish, once out, confined in a pond. Reared to the 
Smolt condition, when the migratory restlessness occurred, some 
might be marked and allowed to go seaward, the condition of those 
left behind being noted. During the second or third season, as the 
case might be, others to be allowed to depart, whilst a few are per- 
manently retained in the pond. 
Three years or less from the commencement of the experiment, 
in the event of a marked grown Grilse or Salmon being caught, 
specimens from the Society’s tanks, the open-air pond, and it to be 
rigidly compared side by side. In the intervals specimens of the 
progressive ages and stages to be preserved in spirits, and, as apparent 
changes take place, figures and annotations thereon duly registered. 
The result of experiments conducted somewhat in the above 
fashion would, I consider, conclusively prove whether or not Salmon 
are temporarily or definitely arrested in their development when 
retained for a considerable period in fresh water. At all events all 
chance of the denial of the parentage of the fish would be obviated. 
Or, again, if the breeders of Salmon, say at the stock-ponds in 
Perthshire, could be induced to fertilize the ova of a full-grown 
Salmon, and transmit the same to the Society, I venture to say the 
ova would be attentively watched during the process of hatching, 
and afterwards the phenomena and stages of growth duly recorded. 
Furthermore, could the bodies of the parents, male and female, be 
likewise transmitted to London for identification, all possibility of 
error would be prevented. As appears plain from what has happened 
with those already reared in the Zoological Gardens, it is of the 
utmost importance that the parents should bear witness of the ova 
being those of genuine Salmo salar. 
It is, indeed, much to be desired that some such well-attested obser- 
vatious should be pursued ; for notwithstanding the asseverations of 
several trustworthy observers, subsequently to be cited, there still 
remains a lurking suspicion that error of data may have crept in. 
I urge therefore upon pisciculturalists, and such as are interested 
in solving a physiological, or, rather, zoological problem of high value, 
the benefit science would derive from the authentication or denial of 
the alleged circumstantial evidence. This is my plea for intruding 
the above suggestions and further memoranda upon the Society. 
I trust that this second notice may stir up those at home, or fish- 
rearers abroad, to follow out the investigation. 
I may premise that I have not entered on the task in a contro- 
versial mood, but to incite further research on the matter. More- 
over it is possible those interested in the question may wish to refer 
to the data, be they merely asserted or be they proven, concerning 
the rearing and detention in pure fresh water for so long a period of 
fish considered to be Salmon. 
It may be pardonable on my part, then, to examine more narrowly 
than heretofore the grounds of opinion, favourable or adverse, espe- 
cially as the whole matter is one involving biological laws of the 
