of t/ie Salmon in Finish Water. 81 



muscle or " thin." From an analysis of one piece of muscle the 

 composition of the whole was calculated. He gives no analyses of the 

 ovaries, and says that he does not possess a sufficient number of com- 

 pleted analyses of the albumin of these structures, and he adopts 30 per 

 cent, as probably too high an amount. 



It was for these reasons that a re-investigation and amplification of 

 Miescher's work appeared desirable, especially as his results have been 

 generally accepted and have been made the basis of very general con- 

 clusions in regard to the metabolic processes in starvation. 



In approaching the subject we had the advantage of a supply of fish 

 from the mouth and upper waters of the rivers at the same periods, and 

 whole fish were placed at our disposal, so that the weight of the muscle, 

 ovaries and other structures could lie directly determined in each ease, 

 and complete analyses undertaken. 



METHOD OF COMPARISON. 



To compare the salmon of different sizes analysed during the enquiry, 

 all weighings of organs and of constituents of organs were expressed in 

 terms of fish of standard length 100 cm. (See page 6.) 



It has been already shown that there is no essential difference 

 between the salmon from the Helmsdale, Spey, and Dee, and that at all 

 seasons they are practically in the same condition. Hence salmon from 

 the different rivers were considered as comparable with one another. 



Instead of following Miescher's method of determining the nature of 

 the exchanges between muscle and ovaries, the following procedure was 

 adopted : 



An average of the weighings and analyses of the different organs of 

 the fish from the estuaries and from the upper reaches of the rivers in 

 the three periods 



May and June, 

 July and August, 

 October and November 



were prepared, and from the differences between these, conclusions were 

 drawn as to the nature and extent of the change. 



Since it is impossible to know whether the fish captured in the upper 

 waters in May and June had left the sea during these months, and had 

 not, in part at least, come up earlier in the year, no definite conclusions 

 are drawn from a comparison of the fish from these two situations 

 during this period. 



On page 75 clear evidence has been advanced that the fish which run 

 in July and August pass up and mingle with the earlier run fish. It 

 therefore seemed justifiable to compare the upper-water fish of July and 

 August with the fish taken in the estuaries from May to August. 



It has also been shown (page 75) that the fish which leave the sea 

 in October and November already full of more or less ripe spawn do 

 not immediately pass up to the upper reaches, but probably remain and 

 spawn in the lower part of the river. Hence the upper-water fish of 

 October and November have to be compared with the fish leaving the 

 sea in the earlier part of the year, from May to August, or with the 

 fish already in the upper water in July and August. 



The following table shows this system of comparison : 



Upper Water. Lower Water. 



July and August Fish compared with May to August Fish. 

 October and November Fish May to August Fish. 



