2 Investigations on the Life History 



over 2000 grrus. The increase in the testes in the male is not so marked, 

 but is sufficiently striking. In April or May these organs are about 

 0-15 per cent, of the weight of the fish, while in November they are 3'3 

 per cent. 



From what are these structures formed ? As they grow, the muscle, 

 as is well known, undergoes marked and characteristic changes. Not 

 only does it diminish in amount as the season advances, so that the fish 

 which have been some time in the river become smaller in the shoulder 

 and back, but it loses its rich, fatty character, while it becomes paler in 

 colour. 



Are these changes in the muscle connected with the growth ot the 

 ovaries and te*tes ? And if so, in what manner and to what extent ? 



On the other hand, in fighting its way up rapids and over falls an 

 enormous amount of muscular work is accomplished by the salmon. 

 Whence is the energy for this work obtained ? Are the changes in the 

 muscle connected with the performance of this work, and if so to what 

 extent are these changes connected with the muscular work, and to what 

 extent with the growth of the genitalia. Lastly, the question arises 

 to what extent do these changes in the muscle modify the value of the 

 flesh as a food stuff. 



In the investigation of some of these questions most excellent work 

 has already been done, not only in Holland and Germany upon the 

 salmon in the Rhine by Dr. Hoek* and Professor Miescher Ruesch,t 

 but also by Mr. Archer, the Inspector of Salmon Fisheries for Scotland, 

 in conjunction with Mr. Grey and Mr. Tosh. The careful series of ob- 

 servations embodied in the Annual Reports J are well worth careful study 

 by the zoologist and the salmon fisher. They should help to dispel 

 the absurd traditions which cling around the history of the salmon, 

 and to pave the way for the complete solution of many of the problems 

 we have enumerated. 



The present investigation is a continuation and amplification of these 

 researches, and would have been impossible without these previous 

 laborious studies. 



Briefly stated, these investigations of the Fishery Board have estab- 

 lished the following facts : 



1st. That some salmon spawn every year, though there is strong 

 evidence that all do not do so. (Eleventh Annual Report, Part If., 

 p. 68.) 



2nd. That the genitalia of fish coming from the sea develop steadily 

 from April on to the spawning time, and that the genitalia of salmon 

 in the earlier summer months develop more rapidly than those of grilse. 

 (Fourteenth Annual Report, Part II., pp. 15 and 21.) 



3rd. That the proportion of the weight of genitalia to the weight of 

 the fish is constant for all sizes of salmon. (Fourteenth Annual Report, 

 Part II., p. 11.) 



4th. That salmon continue to feed while in the sea until September. 

 This is shown, firstly, by the presence of food in the stomach of a certain 

 proportion of the fish captured (Fourteenth Annual Report, Part II., pp. 

 77 to 80.) ; and secondly, by the fact that the fish leaving the sea are 

 somewhat heavier from 2 to 3 per cent. in August and September 

 than they are in the earlier months, whereas if they had entirely stopped 



* Rapport over Statistische en biologische onderyoekingen ingesteld mett behulp van in Neder- 

 land gevangen Zalmen. Dr. P. V. C. Hoek, Wetei.schappelijk Adviseur in Visscherijzaken. 



t Statistische und biofogtache Beitrage zur Kenntniss von Leben des Rheinlachses im Susswasser 

 Dr. F. Meischer Ruesch, Prof. d. Physiol. in Basel. A contribution to the literature of the Berlin 

 Fisheries Exhibition of 1880. Publishers, v^on Metrger & Wiltijr, Leipsic. feee also Histocluinis- 

 che , und Phvsiol gischen Arbeiten von Friedrich Miescher. Bd II. s. 116. Leipzig, 1897. 



t Appendices to Thirteenth and Fourteenth Annual Reports of the Fishery Board for Scotland, 



