ORGAN (TISSUE) DIFFERENTIALS 539 



ever, the characteristic crystal forms of the hemoglobins, which were studied 

 by Reichert and Brown, correspond to primary differentials in transplantation 

 and not to antigens which call forth immune reactions, with which we are 

 here principally concerned. 



There are other characteristics of hemoglobin which may serve to dif- 

 ferentiate the species of animals and even individuals, but no definite cor- 

 respondence has been shown to exist between these characteristics and the 

 relationships of the species or individuals tested. In this regard, according to 

 Anson, Bancroft and Mirsky, there are differences in the maximum spectro- 

 graphic intensity of the bands of oxyhemoglobin in different species, but the 

 distribution of these bands does not correspond to the relationships of the 

 species. Measurements of the distances between the maximum intensities of 

 the A bands of oxygen and carboxyhemoglobin showed individual as well as 

 species differences, but the individual differences could be greater than those 

 between species. In these respects these characteristics behaved therefore to 

 some extent like the blood-group differentials, which are quite unlike the 

 individuality differentials in their distribution. 



3. Thyreoglobulin immune serum reacts specifically with thyreoglobulin, 

 but not with globulins from pancreas and adrenal glands, and the immune 

 sera against the latter substances react specifically only with the globulins 

 from their respective organs. But it seems that in the case of thyreoglobulin 

 the organ-specificity is not an absolute one and that this substance may react 

 also with certain other proteins from the same species. There is an organismal 

 differential present in thyreoglobulin, in addition to its organ- or substance- 

 specificity. The immune serum against thyreoglobulin reacts in a graded way 

 also with the thyreoglobulin from other species and in this case the range of 

 associated secondary reactions is wider than in the case of serum proteins 

 and of hemoglobins. Thus immune serum against thyreoglobulin of one 

 mammalian species reacts in the greatest dilution with thyreoglobulin from 

 the same species, but in stronger concentrations it reacts also with many 

 other mammalian thyreoglobulins ; however, the relative specificity, as mani- 

 fested by the graded character of the reaction, does not seem to be present 

 in every instance, probably owing to an organ- or substance-specificity, which 

 the thyreoglobulins from many species have in common and which may 

 sometimes cover up the organismal-specificity. Still, a species-specificity does 

 exist, as is shown by the fact that immune serum against chicken thyreo- 

 globulin reacts with chicken thyreoglobulin, but not with mammalian thyreo- 

 globulin. As with hemoglobins and serum proteins, so too with thyreoglobulin, 

 absorption of the immune serum by the thyreoglobulin which served as 

 antigen removes also the antibodies against the associated secondary thyreo- 

 globulins, while absorption with an associated thyreoglobulin removes only 

 this secondary thyreoglobulin, but leaves the antibody against the principal 

 thyreoglobulin intact. If for immunization heated thyreoglobulins are used 

 as antigens, the resulting sera contain only organ-specific antibodies, but not 

 antibodies against the organismal differentials (Witebsky). Similarly, 



