103 



The same results have been obtained by Moore c. s. with 

 another method. Knowing the scarcety of Putter's own expe- 

 riments, we may conclude that there are many reasons to be 

 doubtful with regard to his hypothesis, and that for the Holo- 

 thurians we certainly have many reasons of doubt of various 

 nature. 



I do not flatter myself that these few remarks disprove as 

 general an hypothesis as the one of Putter. But I may have 

 succeeded in pointing out some weak spots in his building. 



Addendum after the paper had partly been printed: 



Prof. Dr. W ithrow Morse who had the kindness to look 

 over the manuscript called my attention to the fact that the 

 enzyme which I studied in the starfishes shows more similarity 

 to erepsin than to trypsin. In fact, the former enzyme digests 

 ,,native proteins", albumins and globulins to amino-acids. Trypsin, 

 according to the modern conception, works only on lower 

 peptides, proteoses and peptones, prepared by the gastric pepsin. 



As far as the control experiment on p. 20 is concerned, we 

 must remember the Merck's ,,pure trypsin" is made from 

 extracts of the pancreas and activated by enterokinase from 

 the gut. The latter is mixed with intestinal erepsin. 



The Pn-range of really pure trypsin is very limited. Cf. the 

 recent papers of Me. Clendon and Dernby in the }. Biol. 

 Chem. and the very recent work of Northrup, just published 

 in the J. gen. Physiol. and the J. Biol. Chem. 



