536 THE BIOLOGICAL BASIS OF INDIVIDUALITY 



for the organ-specificity displayed by these organs. According to Witebsky, 

 organ-specific lipoids are present also in kidney and liver. In seeds of plants 

 there occur alcohol soluble prolamins which are identical in very nearly 

 related species and somewhat different in more distant groups (Wells and 

 Osborne, Gortner). These may be considered organ-specific substances. We 

 have referred to these investigations in a preceding chapter, but may discuss 

 here certain points which relate to the problem under consideration. Wells 

 and Osborne found that, as evidenced by the anaphylactic reaction, hordenin 

 from barley and gliadin from wheat are similar to each other; likewise, 

 gliadin and glutenin from wheat behave much alike immunologically. How- 

 ever, a guinea pig sensitized with gliadin reacts somewhat more strongly with 

 gliadin than with hordenin. On the other hand, hordenin and glutenin are 

 quite different, as far as their immunological reactions are concerned ; it may 

 provisionally be concluded that glutenin and gliadin are distinct substances 

 and that the common reaction shown by them is due to a common radicle 

 which they possess. But hordenin does not seem to have this common group, 

 which may correspond to an organismal differential, though it possesses 

 some radicle in common with gliadin, which is not shared by glutenin. This 

 is an interpretation of the facts which would seem more probable than the 

 assumption that we have to deal, in gliadin, hordenin and glutenin, with 

 mixtures of different proteins. 



Also, in the case of animals evidence has been found that the analogous 

 proteins in different organs may contain different radicles which determine 

 the organ-specificity and are associated with certain other characteristics of 

 the protein which determine the organismal differentials. However, as to the 

 character of these gradations in structure, interpretations may differ; it 

 might, for instance, be assumed that the character of the radicle is approxi- 

 mately the same in nearly related species, but differs more strongly in more 

 distant species, although some similarity may still exist in the structure of 

 this radicle even in remote species. It is also conceivable that finer chemical 

 groups are the same, or only very slightly different, in all nearly related 

 species, but that the common basic radicle on which they have been super- 

 imposed is the same in nearly related species, but differs in more remote 

 classes of animals. 



The investigations we have mentioned may serve as examples of organ- 

 specificity, the latter being due to substances contained in these organs and 

 tissues; these substances are evidently the bearers of the organ specificities. 

 It is of interest that these organ-specific substances apparently represent 

 either reserve foodstuffs or secondary cell constituents not exhibiting the 

 most characteristic features of living matter, but constituting end-products 

 of cell differentiation and specialization. Other substances of this kind are 

 pathological in origin. How far the more labile constituents of living cells, 

 as for instance certain nucleo-proteins, possess organ-specificity is as yet 

 unknown. 



We shall now take up somewhat more in detail the question as to what 

 extent organ differentials may be associated with organismal differentials, 



