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AND SummaryThere are significant differences between authors in the values given for the normal range of pH and blood gases in fetal scalp blood during the first stage of labour. Oxygen tensions show the least agreement. The differences cannot be explained by the ways the normal study group were selected (clinically normal ; normal monitored fetal heart rate; healthy newborn infants) nor by choice of measuring system. Both inaccuracy of measurement and variation in the arterial and venous contributions to scalp capillary blood are probably involved. An alternative way of deriving the normal range is described. This gives 7-25 as the lower limit of normal for pH and 60 mm. Hg as the upper limit of normal for Pco,. Definition of hypoxaemia and therefore discussion of its extent and significance remains impracticable at present. However, the normal human fetus does not appear to be in a state of metabolic acidosis in early labour. 13

Summary: A technique is described for the repeated collection of oocytes from rabbits. It involves the use of a Silastic conduit, one end enclosing the ovary and the other lying in the vagina or subcutaneously. After stimulation of ovulation it was possible to collect oocytes from 20 of the 38 rabbits. The implications of the technique, particularly in the field of human infertility surgery, are discussed.