100 



system and this in connection with other statements made by 

 the same author a little further on. 



The author postulates that nine tenths of the C which has 

 been produced by the animals is derived from the soluble car- 

 bonaceous constituents of the sea water which have been used 

 as food. This also seems to be the case for the nitrogen, but such 

 substances account for only 60 of the total N -metabolism 

 however, 40 / comes from the proteins of the body. 



Now here we are : at the very basis of his theoretical con- 

 siderations the N-excretion is supposed to be the product of 

 the protein consumption. On this basis figures on the C-meta- 

 bolism are secured which finally after many detours lead to 

 the above mentioned conclusions. This is apparently a circulus 

 vitiosus, an escape from which does not seem to be very easy. 



Confining ourselves for the present to the N-metabolism, we 

 find another discrepancy. From the fact that in the metabolism 

 experiments the ratio of C : N always remained within the 

 range of 1 : 27 and 1 : 30, whereas in the figures on the com- 

 position (see above) this ratio is between 1 : 5 and 1 : 5.6, 

 ,,folgt schon ohne weiteres dasz Stickstoff erspart wird, indem 

 stickstoffhaltige Abbauprodukte mit Hilfe aufgenommener Kohlen- 

 stofFverbindingen wieder zu Korperstoffen umgearbeitet werden." 



If this is true I do not feel capable of forming a definite 

 opinion on this subject we see another fundamental mistake 

 in Putter's logic. In that case more C than the quantity 

 corresponding with a certain amount of N according to the 

 empirical protein formula, must be produced together with that 

 amount of N. 



Here are two errors in the fundamental figure. If actually 

 nitrogenous water-soluble substances are taken up from the sea 

 water in order to play a role in the N-metabolism, they may 

 have any composition, but that of proteins. The amount of 

 CO 2 resulting from the decomposition and combustion of these 

 substances may have any desired ratio to that of the K j e 1 d a h 1-N 

 and not that of the proteins. At the same time more CO 2 than 

 one would expect is obtained by means of the N-saving system, 

 postulated by Putter. 



From this evidence we see that the conclusion: ,,Es bleiben 

 also 141.2 rngr. Kohlenstoff iibrig, die nicht aus Eiweisz stammen", 

 is excedingly questionable and that the speculations based on this 

 assumption, are to be taken with the greatest reservation. It is 

 of no particular use to go into details about them, it may only 

 be mentioned that the assumption of a ,,Methangarung" and 

 a ,,Buttersaiiregarung" of sugar as a source for the observed 

 CH 4 and H 2 is a rather arbitrary one and that their analogies 

 in mammalian physiology are at their best very hypothetical, 

 as I mentioned in the foot-note of p. 50. 



P u 1 1 e r's deductions are also weakened by the following con- 



