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A very simple application of Bayes's theorem provides a flexible, adaptable and reliable method of deriving confidence limits for nominated functions of several binomial random variables. Tables of confidence coefficients are presented to illustrate the reliability of the method when the functions represent log-odds ratios

The parameters of the growth of human embryos in vitro between fertilization and the biastocyst are described. The data on the cleavage of embryos were subjected to statistical analysis. All the pronucleate eggs examined had two pronuclei. There was no evidence of any oocyte with three or more pronuclei, except in one examined 3 days after insemination, which may have been degenerating. Most eggs which were unfertilized remained in metaphase of the second meiotic division, with an extruded polar body. Spermatozoa were found embedded deeply in the zona pellucida of unfertilized and pronucleate eggs. A total of 417 embryos cleaved in vitro. Mary were in the two-cell stage by 28 hours, four-cell stage at 43 hours, and eight-cell stage at 54 hours. Cleavage patterns were regular in the great majority. Compaction began at the 16 cell stage; the blastocyst began to form between 4 and 5 days after fertilization. Forty-two embryos were examined sufficiently often to make a statistical analysis of their growth in vitro. The mean doubling time of the cells was 15.82 hours approximately. Estimates of the mean midstage times for each stage of division were calculated. The results are discussed in relation to the cure of infertility by replanting human embryos, to the possibility of chromosomal and other disorders arising in the embryos, and to potential scientific studies on early human development.

A direct, rapid radioimmunoassay was developed to measure progesterone in a small sample of milk taken from full milk collected at afternoon milking. Samples were preserved with potassium dichromate and mercuric chloride and transported to the laboratory for assay by a semi-automated procedure. Milk progesterone concentrations were significantly higher in pregnant cows compared with those in non-pregnant cows at 21, 24, 28, 42 and 60 days after insemination. The concentrations were greater in full milk taken at afternoon milking than in first milk taken at morning milking. The concentration of progesterone in milk was found to be correlated with fat content in samples with low progesterone values but not in those with high progesterone values. The success rate of the pregnancy test from a single milk sample 21, 24, 28 or 42 days after insemination ranged from 77·5 to 85·8% for pregnant cows and 85·7 to 100% for non-pregnant cows. The highest success rate was found at 24 days when 142 of 176 pregnant cows (80%) and 25 of 25 non-pregnant (100%) were correctly diagnosed. The use of paired instead of single milk samples gave negligible improvement in success rate. The accuracy of the test in three herds was compared and the incidence of false positive results was analyzed.