320 FOUNDERS OF OCEANOGRAPHY 



were found to be much reduced, and the loss was sufficient 

 to account for all the energy required for the metabolism of 

 the fasting animal. 



The bearing of this result upon Piitter's views is that 

 when a marine animal does not lose weight on being kept 

 without food, it need not be supposed that it is obtaining 

 carbon from hypothetical dissolved compounds in the water, 

 but is merely replacing the loss from its tissues by storing 

 up water. It is evident, however, that this process cannot 

 go on indefinitely. 



Notwithstanding Piitter's statements, which have under- 

 gone so many corrections, until further evidence is forth- 

 coming we may continue to believe that aquatic animals 

 are nourished chiefly by particulate food taken in at the 

 mouth and digested in the alimentary canal. 



The further and final contribution that Professor Moore 

 and the other bio-chemists at Port Erin have made to our 

 knowledge of the metabolism of the sea and the nutrition 

 of marine animals, is that the green plant cell, such as that 

 of the phyto-plankton, is not dependent for either its nitrogen 

 or its carbon upon the amount that may be present in the 

 form of nitrogen salts and as carbon dioxide in the water. 

 They have shown in recent papers before the Royal Society ^ 

 that elemental nitrogen can be obtained from the air through 

 the water, and the very small quantities of nitrates, nitrites 

 and ammonia salts may remain in the water unconsumed. 



In regard to the carbon supply their experiments show 

 that the bicarbonates of magnesium and calcium can be 

 broken up and used by the green plant cell in its nutrition, 

 until the whole stock of bicarbonates in the water has been 

 exhausted. This latest result cuts at the root not only of 

 Piitter's views as to the source of carbon, but also of the 

 law of the minimum (so far as regards nitrogen), as expounded 

 by Brandt and others — to the effect that the amount of 



^ Proc. Roy. Soc, B 91 and 92 (1920). See also Moore's book 

 Biochemistry (1921). 



