K. LANDSTEINER 



897 



that the sensitiveness of individual corpuscles when tested with the same agglutinat- 

 ing serum varied within a wide range (1-32). It could not be established whether 

 corpuscles homozygous with regard to A or B are on the average more sensitive than 

 heterozygous. However, some observations of Oppenheim and Voigt^ on the blood 

 of Chinese seem to support this view. Also the titre of the isoagglutinins varied con- 

 siderably in Schiff's experiments (Fig. 2), the extreme values being 1-16 and 1-2,048, 

 The strength of the agglutinins increases in the first years of life and diminishes in 

 old age. 



^0 



% 



<2 30 



a 20 



10 



% %2 Ibh- ym V256 Vs/2 f/m '/zm 



Fig. 2.- — Agglutinin litre of \arious sera a ( ) and /3 



( ). (After Schiff and Mendlowicz). 



ATYPICAL REACTIONS^ 



The existence of individual blood differences aside from the typical group scheme 

 has been recognized since the beginning of the studies on the subject. Doubtless, 

 apparently irregular reactions were obtained not infrequently by improper technique, 

 for instance, by the use of a method not delicate enough for detecting weak aggluti- 

 nins. Errors in the opposite direction were made by mistaking for isoagglutination 

 other phenomena such as pseudoagglutination and autoagglutination. 



PSEUDOAGGLUTINATION 



It was observed long ago tha t in disea ses, especially in inflamma tory conditions, the 

 erythrocytes have a great tendency to settle, the blood forming a buffy coat. This 

 phenomenon has attracted much attention, and is also employed in practical medicine 

 since the extensive work of Fahraeus. It is due to an increased capacity of the serum 



501 1533- 1924. For statistical data on blood groups in relation to pathological conditions see Hirsz- 

 feld, L., loc. c//.;Thomsen, O. : Ada path, el microbiol. Scandinav., 4, 45. 1927; Johannsen, E. W.: ibid., 

 p. 175. 1927. Tliere is some evidence that under treatment the Wassermann reaction disappears more 

 readily in individuals O and A than in others (Amzel, R.,and Halber, W.: Ztschr. f. Immiinitdls- 

 forsch. 11. exper. Therap., 42, 89. 1925; Gundel, M.: Klin. Wchnschr., 6, 1703. 1927). Oppenheim 

 and Voigt found that group B individuals have a shorter life-span than those of groups O and A. 



' Oppenheim, F., and Voigt, K.: Krankheilsforschung, 3, 306. 1926. 

 ^ Cf. Levine, P.: loc. cit.; Landsteiner, K., and Witt, D. H.: loc. cil. 



