vi CHEMISTRY OF THE PROTEIDS 



3. The arrangement of the primary dissociation-products is based 



on the conception that in the amino-acids we have a recapitu- 

 lation of the same set of changes by which a paraffin becomes 

 converted into an alcohol, then into an aldehyde, and finally 

 into an acid. After this change has occurred at one end of 

 the open-chain-amino-acids, it reoccurs at the other end, and 

 so we pass from mono-carboxylic acids to di-carboxylic acids, 

 and finally, by the central carbon-atoms also becoming ' alcohol- 

 carbons,' we arrive at the very important poly-hydroxy-com- 

 pounds, which seem to play so great a part in the metabolism 

 of carbohydrate-radicals. After having dealt with the mono- 

 ammo-acids the di- amino-acids are discussed on the same 

 principle. Lastly, the union of amino-acids with pyrrol- 

 and benzene-compounds and with sulphur is entered into. 



4. The nitrogen-radicals of the albumin molecule have been fully 



discussed. 



5. The secondary dissociation-compounds have, however, not been 



classified, although the action of alkalies, steam, oxidising 

 media, and sulphur, as well as the changes produced by 

 metabolism, are fully described. 



6. The synthesis of albumins, as far as known up to September 



1905, is given in full. 



7. The action of ferments has, on the whole, been dealt with very 



shortly, so as not to increase the size of the book. The view 

 has been advanced that the chief function of both pepsin and 

 trypsin is to facilitate the disintegrating action of the H- and 

 OH-ions. 



8. The carbohydrate-radicals are fully dealt with because of their 



biological importance, and, for the same reason, throughout 

 the book special attention has been paid to sulphur. 



9. In continuation of my book on Physiological Histology, 



theoretical considerations bearing on the salts of albumins 

 have again specially interested me. There is still far too 

 little attention paid to the salts of albumins, for people will 

 not realise that albuminous compounds in the absence of 

 salts are, as I put it in my first book, in the true sense of the 

 word, dead. Only in the presence of salts will amino-acids 



