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Intact control and sham-operated rats, when given sodium pentobarbitone at 13.30 h on the day of pro-oestrus, mated (controls, 10/12; shamoperated, 13/15) that night and underwent copulation-induced ovulation. However, after removal of the olfactory bulbs only 13 out of 23 pentobarbitone-blocked rats mated. Of the mated animals only six ovulated as compared with ten in the unoperated group and ten in the sham-operated group. The incidence of ovulation in all non-mated animals was low. In addition, the bulbectomized, mated animals which ovulated shed significantly fewer ova than did intact controls and sham-operated rats (6·8 as compared with 11·3 and 13·4, respectively). The incidence of mating in bulbectomized animals was also lower than in sham-operated animals when pentobarbitone was not given (8/16 and 8/11, respectively). Ovulation was essentially complete in all groups except in bulbectomized, mated rats which shed significantly fewer ova. It is suggested that olfactory inputs are important in mediating copulation-induced ovulation in the pentobarbitone-blocked rat and that copulation in the absence of olfactory inputs interferes in some way with the normal sequence of secretion of ovulatory hormone(s) in the non-blocked rat.

Single phase compounds of the form 1-22-3-6, were fabricated using powder metallurgical techniques. Measurements were made of the thermoelectric power, Hall coefficient, electrical conductivity, microhardness and optical reflectance. The electronic properties are discussed in terms of alloy and ionized impurity scattering.

The effects of phytohemagglutinin (PHA) were studied in irradiated mice to see if a definite myeloproliferative effect could be demonstrated in vivo. The data obtained suggested the following conclusions. PHA treatment of the bone marrow donor only, causes a consistent but slight reduction in transplantable spleen colony-forming unit (CFU) content of the bone marrow 24 hr after the last PHA injection, but no change was found in the proportion of the various colony types. PHA treatment of the irradiated recipient of normal bone marrow causes no change in the number of spleen colonies. However, 8-day colonies are only about half normal size, are much more likely to be of mixed cell types, contain many large undifferentiated blastoid cells, but fewer transplantable CFU. The spleen sinusoids are packed with hemopoietic cells. Spleen colonies developing in hosts receiving daily injections of PHA show, in addition to the usual spectrum of cell types, a high proportion of unusual blastoid cells resembling the PHA transformed peripheral lymphocytes seen in vitro. The function of these cells is not known, but they may represent augmented proliferation and/or transformation of stem cells. PHA administered after irradiation significantly increased the number of endogenous spleen colonies, and, at certain doses of irradiation, improved postirradiation survival. PHA administered before irradiation had no effect on the number of endogenous spleen colonies formed, or on postirradiation survival. On the basis of these and other data, possible modes of action of PHA are discussed.