14 



Appendices to Sixteenth Annual Report 



the difference is sufficiently marked to enable the former to be- 

 distinguished from the latter and to afford a guide as to the date of 

 the immigration of the latter from the sea. 



The evidence which has been adduced may be divided under two- 

 heads, viz. : — First, as to the question of whether salmon entering the 

 rivers in spring can develop ripe ova and milt without revisiting the 

 sea ; and, second, whether they do remain in fresh waters until the 

 spawning season, and, if so, whether they form the breeding stock in 

 the head waters of the rivers, leaving the lower reaches for the later 

 arrivals. 



With regard to the first question : — 



1. The greater weight of the genital organs in " clean " salmon taken 

 in March and April, as compared with those in kelts, shows that the 

 growth of these organs has already begun in fish coming in from the 

 sea in the early months ; and the gradual increase in the weight of these 

 organs in every succeeding month, that growth proceeds with great 

 regularity until maturity is reached. Every different stage of develop- 

 ment seems to be represented in the specimens which have been 

 examined, and the small size of the genital organs in the early months 

 would seem to be simply due to their being at that time in the earlier 

 stages of development (Fourteenth Annual Report, pp. 14 and 16 ; 

 Special Report, pp. 68, 72, and 74). 



2. The greater weight of the genital organs in fish taken in the upper 

 waters, as compared with those in fish taken at the mouth in the same 

 period, denotes that not only has development not been arrested in fish 

 which entered the fresh water early in the season, but on the contrary 

 that it has advanced further in them than in the later arrivals (Special 

 Report, pp. 68 and 72). 



3. The experiments conducted on the river Aaensira in Norway show 

 clearly that salmon entering the fresh water in June, when the genital 

 organs in females are one-tenth, and in males one-thirteenth, of their 

 ripe weight, can develop ripe ova and milt without revisiting the sea 

 (Twelfth Annual Report, p. 55 ; and Fourteenth Annual Report, p. 14). 



4. The diminished weight of fats and proteids in fish taken in the 

 upper waters in October and November as compared with fish coming 

 in from the sea between May and August, the atrophied condition of 

 the lining membrane of the stomachs and intestines, and the very low 

 digestive power of these organs, show that the material used in the 

 construction of the genitalia and the source of energy required during 

 the sojourn of the fish in fresh water are derived from the fats and 

 proteids stored in their bodies, thus making them independent of food 

 while in the river (Special Report, pp. 13, 23, 36, 93, 120, and 170). 



With regard to the second question. Dr. Noel Paton draws attention, 

 in the first place, to the length of the fish supplied from the upper and 

 lower waters respectively (Special Report, pp. 68 and 75). He points 

 out that the length of the fish coming to the mouth of the river is 

 " practically the same from May to August. But in October and 

 " November a markedly larger class of fish appears in the estuaries. In 

 " the upper reaches, however, the size of the fish remains constant until 

 " October." Since, in the case of the fish he examined, fish of a particular 

 size were asked for, the circumstance of large fish being sent from the 

 mouth and small fish from the upper waters does not prove that large 

 fish were not present in the upper watei-s, or that they might not arrive 

 there a few weeks later. But it does appear to show that fish of the 

 desired size were not coming in from the sea in October and November, 

 which conclusion is supported by the figures given in Tables I., II., and 

 XI. (Special Report, pp. 10, 11, and 69), and that the smaller class of 



