of the Salmon in Fresh Water. 



127 



three periods being 210, 218, and 209 grammes of nitrogen in the fish 

 of standard length, the average for the year being 213. Some excep- 

 tions to this were observed, notably Fish 15, 17, 29 (vide Table 1), the 

 nitrogen of these amounting to only 196, 177, and 177 grammes per 

 fish of standard length. Nos. 29 and 1 7 were exceptional in other ways. 

 No. 29 had wounds on its side, No. 1 7 had an empty gall bladder, but 

 about No. 15 nothing abnormal is noted. 



The upper- water fish show marked changes in the amount of muscle 

 nitrogen, the amount decreasing as the season advances, the decrease 

 being much more marked in the later part of the season. The amount 

 of aitrogen per fish of standard length was in May and June 188 grms., 

 in July and August 185 grms., in October and November only 113 

 grms. 



The large fall of the amount of muscle nitrogen in October and 

 November will be considered after the gain of nitrogen by the ovaries 

 has been discussed. 



A comparison of the upper-water fish with those of the estuary shows 

 that all through the year the upper-water fish have less muscle nitrogen 

 than the estuary fish, the deficit being greatest in October and 

 November. 



///. Percentage of Proteids in the Ovaries. An examination of the 

 figures given in Tables 1 and 2 shows that there is throughout the 

 season a steadily increasing percentage of proteid matter in the ovaries, 

 both in estuary and in upper- water fish. In estuary fish the amount of 

 nitrogen in the ovaries rises from 3'19 per cent in May and June to 3'36 

 per cent in July and August, and 3'82 per cent in October and 

 November. In the upper-water fish the corresponding figures are 2-97 

 per cent, 3*78 per cent, and 4'05 per cent. 



IV. Total Proteids of the Ovaries This also shows a steady increase 

 during the season ; not only are the ovaries richer in nitrogen as the 

 season advances, as stated above, but they are increasing in weight 

 the whole time. The increase of proteid takes place both in estuary 

 and in upper-water fish, but it is greater in the upper water fish. 

 These changes are shown in the following table. 



TABLE VI. 



Showing amount of ovarian nitrogen per cent, and in fish of standard 

 length : 



Comparing this Table with that referring to the total amount of 

 muscle nitrogen during the three periods, it is evident that it is during 

 the time of the greatest ovarian increase that the muscle loses most. 



A comparison between the loss of proteid from muscle and the gain of 

 proteid by ovaries, when the salmon is in fresh water, is shown in the 

 following table, the fish being compared with each other in the manner 

 adopted by Dr. Paton (p. 81). 



