896 THE HUMAN BLOOD GROUPS 



Jones, Hirszfeld, Smith,' cf, CoUon'), The appearance of the agglutinogens precedes 

 that of the agglutinins so that ordinarily at birth the group of the cells can already 

 be determined although, according to Happ,^ agglutinogens may still develop after 

 birth. The groups are definitely established also in the serum within the first or second 



Fig. I. — Sensitivity of various red cells A ( ) and B ( ). (After Schiff and Hiibener) 



year of life. The idea that discrepancy of the groups of mother and infant — so-called 

 "heterospecific pregnancy" — may be the cause of pathological conditions such as 

 eclampsia, icterus neonatorum, and of general deleterious effects on the infant has 

 been discussed by various authors (cf. Hirszfeld,^ Preger,^ Smith) but these investi- 

 gations did not yield consistent results. 



A study of the quantitative variations of the agglutinins and agglutinogens 

 was undertaken by several workers such as Dyke,'^ Jones and Glynn,^ Schiff,* and his 

 collaborators.' Some results obtained by Schiff are presented in Figure i, which show 



' Smith, C: Am. J. Dis. Child, (in press). 



2 Collon, N. G.: Arch. int. med. exper., 3, 237. 1927. 



3 Happ, W. M.: J. Exper. Med., 31, 313. 1920. ■' Hirszfeld, L.: loc. cit. 

 5 Preger, A.: Ztschr.f. Immunitdtsforsch. ti. exper. Therap., 53, 192. 1927. 



^ Dyke, S. C: Brit. J. Exper. Path., 3, 146. 1922. 



7 Jones, A. R., and Glynn, E. E.: J. Path, b' Bad., 29, 203. 1926. 



* Schiff, F., and Hiibener, G.: Ztschr.f. Immiinitatsforsch. u. exper. Therap., 45, 207. 1025; 

 Schiff, F., and Mendlowicz, L.: ibid., 48, i. 1926. 



?With regard to the possibility of an increase in agglutinins in pathological conditions see 

 Schneider, P.: Ztschr.f. d. ges. exPer. Med., 36, 153. 1923; and Mino, P.: Deutsche med. Wchnschr., 



