SEA-FISHERIES LABORATORY. 409 



contact with the gills or other absorptive organs, the 

 lobsters in our experiments would be required to com- 

 pletely clear 160 litres, the fish 450 litres, and the octopus 

 600 litres of sea-water daily of all trace of organic matter. 

 Even if Putter's own most recent figures for organic 

 matter of 4 milligrams per litre be taken, then the figures 

 become 40, 112, 150 litres, and this suggestion, especially 

 in absence of any attempt at direct experimental proof, 

 seems to us to be ruled out by its inherent absurdity. It 

 is impossible to believe, in absence of all attempt at proof, 

 even admitting that sea-water contains 4 parts in a 

 million of some hypothetical and unknown form of organic 

 matter, that this organic matter can, in some way, be 

 entirely removed from the water passing in contact with 

 the gills of a fish, of only about 250-2T0 grams in weight, 

 to the extent of at least 112 litres of sea-water every 

 twenty-four hours. 



Such an uptake of dissolved organic matter in 

 exceedingly dilute solution from a comparatively large 

 volume of sea-water could only occur if, in the fish gill, 

 there were exposed a substance with a specific high avidity 

 for the dissolved organic matter, comparable to that of 

 haemoglobin and similar bodies for the dissolved oxygen 

 of the water. Both the dissolved organic matter and the 

 body possessing ability for its absorption are, however, 

 purely hypothetical, and so the Putter hypothesis rests on 

 no observed facts, and is incompatible with all recent 

 determinations. 



It is, in our view, definitely settled by experiment, 

 thai sea-water does not contain any appreciable amount of 

 organic mailer capable of acting as a autrienl medium 

 lor aquatic animals. 



In iliis paper we have also obtained, over Longer 

 periods, figures indicating the rates of oxidation in Larger 



