AMYLOID 



349 



The variations in the composition of the different amyloids, 

 as shown in the above table, indicate that the proteid group 

 may vary in different organs or in different cases, and also 

 indicate that the " amyloid-like " substance of normal vessels is 

 not the same as the pathological substance. Corresponding 

 variations were found in the apportionment of the sulphur 

 between that which is in the form of oxidized sulphur and the 

 unoxidized sulphur. The proportion of the different amino- 

 acids in the proteid constituent of amyloid is strikingly like 

 that of thymus histon, and entirely dissimilar to the apparently 

 closely related elastin, as shown by the following table : 



TABLE II. 



This carries out the resemblance of amyloid to nucleoproteids, 

 and, likewise, Neuberg found amyloid very slowly digested by 

 pepsin, and much better by trypsin, although less rapidly than 

 simple proteid ; it is also destroyed by autolytic enzymes, for 

 amyloid tissues readily undergo autolysis. Neuberg considers, 

 from the above results, that amyloid is probably a transforma- 

 tion-product of the tissue proteid, similar to the transformation 

 of simple proteids into protamins that occurs in the testicle 

 of spawning salmon as they go up the streams, as shown by 

 Miescher's classical studies. 



Krawkow considers that amyloid differs from normal chon- 

 droitin-sulphuric acid compounds, such as cartilage, in that in the 

 latter the acid radical is in a loose combination with the proteid, 

 while in amyloid the combination is a very firm one, perhaps in the 

 nature of an ester. The occurrence of the typical amyloid reac- 

 tion in what appears otherwise to be normal cartilage, occasion- 

 ally observed in senile tissues, may be due to the transformation 

 of loosely bound into firmly bound chondroitin-sulphuric acid. 

 In any event, amyloid is not essentially a pathological product, 



