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Postnatally, XO mice have approximately half as many oocytes as their XX sisters. A quantitative histological analysis of XO and XX ovaries throughout oogenesis (14 1/2-24 1/2 days post coitum) revealed that this oocyte deficiency in XO mice is due to excess atresia of oocytes at the late pachytene stage (19 1/2 days post coitum). Female mice heterozygous for a large X inversion (In(X)/X mice) were also found to have excess atresia at late pachytene. It was suggested that in XO mice it is the presence of an unpaired X chromosome, and in In(X)/X mice, the incompleteness of X chromosome pairing, which leads to this excess oocyte atresia. A new quantitative histological procedure which was developed for the analysis of perinatal mouse ovaries is also described.

Anaemia during pregnancy compromises the health of mothers in traditional cultures, where women tend to have several children close together after marriage, with an inadequate interval to replenish nutritional stores. Their infants also appear to be at increased risk of developing iron-deficiency anaemia, undetected at birth.

This paper surveys the literature on, and examples of current implementation of, carbon taxes and carbon emission permits. It sets out the theoretical basis for these instruments, with special reference to the revenuerecycling and tax interaction effects. This theoretical work concludes that instruments which raise revenue which can be recycled so as to reduce preexisting distortionary taxes are significantly less costly than those which do not. The paper then reviews the sizable literature on the distributional effects of these instruments, especially with regard to industrial competitiveness and regressive effects on low-income groups, evaluating attempts to mitigate these where they are perceived as unacceptable. The paper concludes that such efforts at mitigation, while possible, can substantially reduce the efficiency benefits of the instruments. The projected costs of carbon taxes depend on a wide range of assumptions. This is still a contested area, but the paper concludes that, on a range of plausible assumptions, these costs need not be high. Finally the paper notes that early evaluations of the environmental effectiveness of carbon taxes have been generally positive. This suggests that, if concern about anthropogenic climate change continues to increase, more countries will introduce carbon taxes and emission permits, with the latter increasingly auctioned.

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