Life-history of Salmon. 100 



particular as it contains, as it seems to me, a most remarkahle 

 confirmation of my hypothesis. It is the ' Report ot" Investi- 

 gations on the Life- History of Salmon,' published by the 

 Fishery Board for Scotland in 1898. This report consists of 

 a series of papers by several experts. There is hardly one of 

 these which does not bear directly upon my hy|)0the3is ; in 

 fact the support which they afford is, to my mind at all 

 events, so obvious, that when quotin<^ the more important 

 })assages I shall be saved from lengthy comments. Com- 

 mencing with the " General Introduction" by Dr. D. Noel 

 Paton, we find the statement that: — 



" In the female the growth of these [the genital organs] is 

 enormous. In April or May the ovaries constitute only about 

 1*2 per cent, of the weight of the fish, in November they are 

 no less than 23*3 per cent. In a fish of 30 lbs. in the spring 

 they weigh about 120 grms., in November they weigh about 

 2000 grms. The increase in the testes in the m de 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." (pp. 1 & 2). 



Surely then, if the above statement be true, here at the 

 outset we have sufficient reason to suspect, as I suggested in 

 my paper, that "in the effort to produce as much spawn as 

 possible the whole metabjlisin is upset." Nothing would 

 seem more likely than that such a concentration of energy 

 upon the formation of milt and ova should cause the total 

 urdiinging of the normal processes of the fisli's body. 



Continuing, Dr. Noel Paton asks the question, " From 

 what are these structures formed?" And before attempting 

 an answer he points out that " as they [the genitalia] grow, 

 the muscle, as is well known, undergoes marked and charac- 

 teristic changes. Not only does it diminish in amount as 

 the season advances, so that the fish which have been for 

 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" (p. 2). 



Evidently then, so far at least as the muscles are con- 

 cerned, the metabolism of the body is upset, and instead of 

 being anabolic becomes markedly katabolic. 



It is part of the duty of the various authors of the report to 

 discuss the connexion, if any, between the changes in the 

 muscles, the growth of the ovaries and testes, and the source 

 of the energy used up by the salmon in fighting its way up 

 stream, often up rapids and over falls. " Are the changes 

 [it is asked] in the muscle connected with the performance of 

 this work ; and if so, to what extent are these changes con- 

 Amnlc Mag. X. Hist. Ser 7. Vol. ix. 9 



