KATE OF RENEWAL OF THE FISH SKELETON 



209 



showed the total absence of iion-inineial constituents. The bones were dried at 

 105° and dissolved in 2 ml 0.5 N HCl. The solution was brought to 25 ml and an 

 aliquot was used, as described above, in the radioactive measurements, while 

 llie other aliquot was fakcMi for colorimetric determination. 



UPTAKE OF LABELLED PHOSPHATE BY THE FISH 



The uptake of IuIk'HimI phosphate by the fisli most j)n)baljly takes 

 place either through the gills or tlirough the digestive tract. While water 

 passes the surface of the gills, some phosphate may reach the circulation. 

 An increase of the water volume passing the gills may in this case be 

 expected to lead to an increase in the phosphate uptake. Therefore, 

 we have compared the phosphate uptake by fish kept in water rich 

 in oxygen with the uptake of phosphate by fish in water containing 

 but very small amounts of oxygen. While a group of fish was kept for 

 a day in 2 litres of labelled sea- water saturated throughout the experi- 

 ment, another group was kept in 2 litres of labelled sea-water to which 

 no oxygen was added and in which other sticklebacks were previously 

 kept in order to remove much of its air content. As seen in Tal)U^ 2. 

 the average uptake of ^^p l^y the two groups of fish practically does 

 not differ. 



Table 2. — Uptake of ^-Pby Fish Kept in Oxy- 

 gen-rich AND Oxygen-poor Water in the Course 

 OF 24 Hours 



Weiijht of fisli in giu 



Total activity present in 1 gm fish 



water ricli in 

 oxygen 



water poor in 

 oxygen 



14 Hevesy 



