of this technique as a method of hydrolysis of 17-ketosteroid conjugates, owing to the poor total yield, and low extraction of androsterone and etiocholanolone.The conclusion is that a moderate hydrolysis of the usual type in which artefacts are created but measurable, is preferable to one in which the total yield of 17-ketosteroid is impaired.

The effects of the folic acid antagonist, 4-amino-N10-methylpteroylglutamic acid (methotrexate), and varying doses of folic acid were studied on superovulated immature rats. Methotrexate and folic acid were used alone and in combination with oestrone.The parameters selected for study were organ weights and ovum counts. The administration of methotrexate (200 \g=m\g./rat), folic acid (400 \g=m\g.) or oestrone (500 \g=m\g.)partially inhibited ovulation. When given in combination with oestrone, both methotrexate and folic acid (50\g=m\g.) reversed the fall in ovum counts produced by oestrone.Because either a deficiency or an excess of folic acid partially inhibited ovulation, it is concluded that folic acid plays a significant role in induced ovulation in the immature rat. These effects are probably interrelated with the action of oestrogen.In hypophysectomized immature rats, gonadotrophins increased ovarian and uterine weights when compared with those in untreated hypophysectomized animals, but the simultaneous administration of either methotrexate alone or combined with oestrone prevented these effects. Similar treatment of intact animals showed no differences in ovarian and uterine weights.

A research project supported by the Atomic Energy Commission was undertaken in this laboratory to investigate the effects of irradiation on mammalian ova in vitro. I n order to develop needed techniques and to comprehend the effect of radiation on germ cells in general it was thought profitable to first study the effect of radiocobalt irradiation on spermatozoa in vitro.I t is known that during spermatogenesis the male germ cells are extremely sensitive to irradiation while the mature spermatozoa are extremely resistant to such exposure. X-irradiated spermatozoa may retain both their motility and fertilizing capacity but are unable to initiate normal development of the fertilized ova due to latent damage to the chromatin. I n their extensive study of the effects on embryonic development of X-irradiation of rabbit spermatozoa in zdro, Amoroso and Parkes ('47) concluded that exposure of spermatozoa to 50 r and 100 r did not interfere with fertilization, segmentation of the ovum, or embryonic and fetal development ; following irradiation with 500 r, litter size was reduced and with 1,000 r no implantation "as observed; with 2,500 r all tuba1 ova

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