PROCEEDINGS, MAY. XV 



Mr, R. M. Johnston followed with a paper on the same subject, 

 dealing in a scientific manner with the evidence as to the fish 

 we have secured. He was not aware, in preparing his paper, that 

 Mr. Seager was engaged in writing such an important paper, and 

 would therefore omit the brief reference he had made to the history 

 of the subject, which Mr. Saager had already so exhaustively dealt 

 with. Taking up the subject from the discovery of the proper means 

 of conveying the ova, he spoke in very high terms of the services 

 rendered by Sir Thomas Brady and Dr. Agnew, and said the problem 

 to solve was whether the progeny of the rea.\Sa/mosalar when liberated 

 perpetuated their species in Tasmanian waters ; for no specimen hitherto 

 caught in Tasmania could be decidedly classified with the S. salar of 

 Europe. But if the fish in the water here referred to as .S'. tnUta and 

 S. fario, liberated in IS66. what had become of the far greater number 

 ot S. salar then liberated ? The theories advanced to account for the 

 supposed non-appearance of S, salar might be briefly referred to as the 

 hybrid theory ; the extinction theory — that the environment, food, 

 climate, and enemies had killed them ; and the exodus theory — that 

 they had wandered away from our shores and had not returned. That 

 hybrids of salmoniiht' existed was confirmed in other parts of the world, 

 but the facts of the history of acclimatisation here would not admit of 

 the assumption that hybrids were introduced, as there were five ship- 

 ments obtained at difi'erent times, different places, and by different 

 people all skilled in the work. Granting that a few mistakes might 

 occur, it was preposterous to assume that hybridism should have 

 resulted in all the cases, and the facts stated were sufficient to 

 dismiss it at once. The extinction theory was more reasonable, as 

 it was conceivable that extremes of temperature, or sucli enemies as 

 the barracouta, might account for the extinction, Still, the variation 

 in the temperature of deep water was not very great, while in the 

 shallow ponds of the Plenty they had the undoubted progeney of Salmo 

 salar, not only surviving, but actually bred in the ponds. There was 

 no means in the colony of obtaining accurate information of temperature 

 at a depth, and it was absurd to gauge isotherms on shallow sand flats, 

 where in England an equally high temperature will be discovered. At 

 the Clyde sea area and other places a series of temperatures had been 

 taken with deep sea thermometers, revealing the fact of very slight 

 variations at a depth. Looking at the characters of the waters here, 

 there was every reason for distrusting the temperature taken on a sandy 

 shallow. Regarding the presence of euemies such as the barracouta, 

 there was no reason for supposing that the Salmo salar should fall a 

 prey to these fish, while others survived. The exodus theory also 

 depended upon temperature. It was not unreasonable, but the evidence 

 was against it. Mr. Kent had suggested that the fish had wended 

 their way towards Japan, but this was improbable, and opposed to 

 the known instincts of all animals who were prompted to return, if they 

 wandered, to the homes of their ancestors. If the heat caused them to 

 migrate they would travel south, and be lost in the wilderness of waters 

 in the Antartic Ocean. The question then was, had the Salmo salar 

 migrated lo the waters around the South Pole, or was the migratory 

 fish now in our waters the true descendants of the Salmo salar of 

 Europe, modified by the difference of enivronmeut. The classifications 

 of mugeums were not reliable when applied to the various intermediate 

 forms of the fish marVel, where the doubts of the classifiers were set 

 aside as the vivialities of naturalists and the fish bought and sold as 

 salmon. Nor did individuals agree on the points of determination. 

 \yhat nituralist was prepared to declare the limits of individual varia- 

 tion in form, colour, etc., in the growth of one fish through its various 

 stages, under changes of food, climate, and other circumstances of 

 environment? He did not urge these remarks against the classification 



