A practicable definition of the term hypertension is attempted, its main causes are mentioned, and essential hypertension is briefly discussed. A practical classification is given of conditions causing hypertension during pregnancy, namely eclamptogenic toxaemia, essential hypertension and chronic glomerular nephritis, the last two of which may be either uncomplicated or complicated by superimposed toxaemia. The most important differential diagnostic criteria of these conditions are summarized under the following headings: History (personal and family), age, parity, onset, hypertension, oedema and weight increase, urine (quantity, proteinuria, microscopy), renal function (concentrating power, urea clearance, renal blood flow or diodrast clearance, glomerular filtration or inulin clearance, filtration fraction), blood chemistry (non-protein nitrogen, serum proteins, alkali reserve), fundus oculi, cardiovascular pathology and symptomatology. Reasons are advanced for the difficulty in definitely differentiating these conditions in a case seen later than the 20th to the 24th week of pregnancy. The greatly increased incidence of toxaemia and eclampsia in previously hypertensive patients is pointed out. The relationship between proteinuria and foetal death in utero is demonstrated. The extreme importance of repeated examinations of the fundi oculi in all types of hypertension in pregnancy is emphasized. Hallum's excellent descriptionption of the fundal changes in these conditions is summarized.
(Concluded from p. 170, 10 March 1951) The distribution of the blood groups ABO, MN, P and Rh in the South African Bantu has been studied. The calculated frequencies of the genes demonstrate that this race is genetically homogeneous and possesses a distribution of genes which is unique among the peoples of the world. The theories of heredity of the blood groups are discussed in the light of the findings, particularly the genetics of the Rh system. Evidence is adduced in favour of the theory of multiple allelomorphs for composite Rh genes at a single locus on the chromosome.