66 THE PROTEOMORPHIC THEORY AND THE NEW MEDICINE 



The simplest polypeptids (di-peptids) result from the union 

 of two amino-acids; more complex ones from the combination 

 of three or four or five amino-acids. The molecule of a poly- 

 peptid is, therefore, complex as compared with the molecule of 

 an amino-acid ; but, on the other hand, it is relatively simple as 

 compared with the molecule of peptone. In other words, a mole- 

 cule of peptone could be cleaved, perhaps by successive stages, 

 to form a goodly number of molecules of the most complex poly- 

 peptids yet synthesized. 



It is important to get clearly in mind this position of the poly- 

 peptids as nitrogenous compounds, which are considerably more 

 complex than amino-acids, and yet very simple indeed as com- 

 pared even with peptones, which in turn have but a fraction of 

 the complexity of the original protein from which they are hydro- 

 lyzed. There are some thousands of atoms in a molecule of pro- 

 tein ; some hundreds in a molecule of peptone ; some scores in a 

 molecule of the more complex polypeptids ; and, as we have 

 seen, less than two dozen in the molecule of an average amino- 

 acid. 



It is familiarly known that the giant protein molecule which 

 comes into the stomach as the chief constituent of proteid foods 

 is hydrolyzed and disintegrated to the peptone stage (via pro- 

 teoses) by the enzymes of the digestive tract. Just what happens 

 to the peptone after it is absorbed into the intestinal wall has 

 been a matter of dispute. There is no question that it is further 

 metamorphosed, for it does not appear as peptone under normal 

 conditions in the blood stream. The balance of authority lends 

 strong support to the belief that the peptone is further hydro- 

 lyzed in the intestinal wall, until its molecules reach or approx- 

 imate a degree of smallness that makes them available for the 

 use of the various body-cells to which they will presently be 

 carried by the blood stream. It seems highly probable that they 

 enter the blood as amino-acids, of various types, and are thus 

 carried to the tissues as dispensers of building materials, among 

 which each individual type of cell may select in accordance with 

 its needs for the different body proteins are made up of dif- 

 ferent combinations of amino-acids. 



But we have seen in our earlier discussions that it happens on 

 occasion that portions of the proteins taken into the stomach 

 find their way through the intestinal wall unmodified, or not 

 greatly modified, by the digestive ferments, and introduce a com- 

 plication in the problem of assimilation ; a complication which, 

 according to our thesis, is met by the activities of the leucocyte. 

 If the gigantic molecule of protein thus finds its way on occa- 

 sion through the intestinal wall, it seems plausible to suppose 

 that the comparatively small molecules of the polypeptid order 



