156 Investigations on the Life- History 



14. THE EXCHANGE OF IRON BETWEEN MUSCLE 

 AND OVARIES OF SALMON. 



BY E. D. W. GREIG, M.B. EDIN. 



It has already been shown in another part of this Report (p. 147) 

 that iron is present in the paranuclein of the ovaries of salmon. 



This investigation was undertaken to determine (1) whether the 

 quantity of iron present in the ovaries increases during their growth, and 

 if so (2) from what source it is derived. In considering the possible 

 sources of supply, it was at once obvious that the food ingested could l>e 

 excluded, as evidence has been adduced (p. 13 etseq.) to show that salmon do 

 not take nourishment during their sojourn in the river. Did the ovary, 

 then, as in the case of its fats and proteids, obtain the whole of the 

 iron required from the muscle ? or did part only come from muscle, and 

 the remainder from some other source, e.g., liver or blood ? 



To elucidate this the amount of iron in the muscles, ovaries, and in 

 the livers of two typical fish leaving the sea in May, and in two typical 

 fish from the upper reaches of the river in October, was determined. 

 The very tedious nature of the analyses prevented a krger series of 

 observations being accomplished. The close correspondence in the 

 results obtained, however, indicates that the conclusions may be safely 

 accepted. 



Method. The method employed in the analyses was that devised by 

 Stockman (Journal of Phys., xviii., p. 485, 1895). The steps may. for 

 convenience, be briefly recapitulated here. 



Portions of the dried residue of the tissue, after extraction with 

 ether, were dried in the hot-air chamber and weighed. In the case of 

 the livers, a portion of the organ was pounded down and extracted with 

 alcohol for several days, and then dried and weighed. They were then 

 completely ashed in porcelain. The ash was extracted overnight with 

 strong HC1, and next morning dilute H 2 SO 4 was added, and the 

 whole heated. It was then filtered through ash-free filter paper, and 

 the filtrate placed on the steam bath to drive off the HC1. The iron 

 was then left dissolved in the H^SO^ A few drops of potassium per- 

 manganate were added, and it was set aside for several days. If the 

 colour remained (showing that all organic matter was destroyed), it wa* 

 then reduced with zinc, and titrated with a standardised solution of 

 potassium permanganate. 



All the reagents, &c., were tested, and found iron-free. 



The following Tables give the results of these analyses in grins. : 



