ii PERCENTAGE-COMPOSITION 67 



however, hardly in store for us, because the discovery of indol-amino- 

 propionic acid, of phenylalanin, and of cystin allows us to refer all the 

 secondary dissociation-products directly to the known primary ones. 

 The only possibility which suggests itself is that, in addition to serin 

 or amino-oxy-propionic acid, tetra-oxy-amino-caproic acid, and diamino- 

 trioxy-dodecanoic acid, yet other oxy-acids may be discovered. If we 

 take globin, which has been dissociated more than any other albumin, 

 as an example, we find, on adding together all the known dissociation- 

 products (after deducting the corresponding amounts of water), that the 

 sum-total shows a deficiency in oxygen and an excess of carbon and 

 nitrogen. Therefore certain compounds must exist in the albumin- 

 molecule, such as oxy-amino-acids or carbohydrate radicals, which are 

 richer in oxygen. 



We are as yet imperfectly informed as to how the known dissocia- 

 tion-products are distributed over the individual albumins. Kossel 

 and Dakin 1 found, for example, that arginin in certain albumins 

 amounts to more than 83 per cent of the total amount, while in others, 

 such as maize-albumin, it is present only to the extent of 1 '8 per cent. 

 Kossel and Soare, in the same paper, point out further that the 

 amount of arginin varies even for the different albumins of one and 

 the same muscle. The arginin fraction amounts to 2*49 per cent in 

 the albumins which are readily precipitable by ammonium sulphate, 

 while in the non-precipitable albumins the fraction only amounts to 

 0'64 per cent. Lysin is even completely absent in the alcohol-soluble 

 albumins of wheat and maize. In the protamins only 4 to 5 out of a 

 possible of 17 to 18 primary dissociation-products are found, as has 

 already been expressed in Kossel's table given above on p. 65. 

 Ammonia and the hexone bases have been determined most fre- 

 quently, and their values have been ascertained most accurately 

 The systematic preparation of mono -amino- acids according to E. 

 Fischer's method has been carried out, so far, only in the case of a 

 few albumins, and even in these cases only minimal values have been 

 obtained. All the older estimations of the mono-amino-acids, except 

 those of aspartic and glutaminic acids and of tyrosin, are of but little 

 value. 



Siegfried ' 2 has further raised the question as to whether we have 

 any right to assume the dissociation-products to be preformed. He 

 believes if we were to add together the whole of the C and the N of 

 all such dissociation-products as can be obtained by acting, for example, 

 on any given albumin with hydrochloric acid, that the sum-total of 



1 A. Kossel, Berliner Wn. Wochensch. No. 41, Oct. 1904, p. 1065. 



2 M. Siegfried, Ber. d. Sachs. Ges. d. Wiss. zu Leipzig, 1903, p. 85. 



