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To understand the observational properties of cosmological models, in particular, the temperature of the cosmic microwave background radiation, it is necessary to study their null geodesics. Dynamical systems theory, in conjunction with the orthonormal frame approach, has proved to be an invaluable tool for analyzing spatially homogeneous cosmologies. It is thus natural to use such techniques to study the geodesics of these models. We therefore augment the Einstein field equations with the geodesic equations, all written in dimensionless form, obtaining an extended system of first-order ordinary differential equations that simultaneously describes the evolution of the grav-itational field and the behavior of the associated geodesics. It is shown that the extended system is a powerful tool for investigating the effect of spacetime anisotropies on the temperature of the cosmic microwave background radiation, and that it can also be used for studying geodesic chaos.

Proceduye 12 in. apart, each covered by a slide which the monkey could push to obtain a half peanut. A sliding opaque panel could be interposed between the monkey and the testing tray, lind a sliding one-way-vision screen concealed E from S's view. The following tasks were used: Delayed alternation. The two food cups were covered by unpainted aluminum slides. PaUern discrimination. Each of the slides used to cover the two food cups had a yellow pattern painted on black background. The rewarded pattern formed a cross and the unrewarded one the sides of a square, all lines being 4~em. long and 1 em. wide. Object discnminalion..A black, dome-shaped wooden block (rewarded) and a white triangular block, each 7 em. wide at the base and 17 em. high, were used to cover two food wells, set 12 in. apart. The Ss pushed the objects aside.to expose the food wells.

STUDIES CONCERNING the effects of barbiturates on the delayed-response and delayed-alternation performance of primates with frontal lesions have yielded discrepant results. An experiment on four monkeys by Blum et al. (1) failed to confirm the findings of improvement with sedation obtained on two monkeys by Wade (4) and on two baboons by Pribram (2). Two consistent differences among the experimental ,conditions employed in these studies have been noted by Blum and co-workers. Their animals were tested late, two at six months and two at two years postoperatively, and all scored significantly above chance prior to injection of the drug. In contrast, Wade's and Pribram's animals were tested early, three months postoperatively, and performed at only a chance level before drug administration. Blum and co-workers suggest that in the latter animals Nembutal may have hastened an improvement which would have occurred without the use of sedatives if sufficient time and training had been allowed following operation. To test this hypothesis, an experiment on the effects of Nembutal was performed on a group of baboons who had received six months of intensive postoperative training on delayed-response and delayed-alternation problems. At the end of this period, which was comparable to that allowed two of the monkeys studied by Blum and co-workers, the delayed-alternation scores of half the animals were at a chance level and of the other half at a level significantly above chance. A finding of improvement with sedation., par-ticuIarly in those animals who were already performing reliably better than chance, would be inconsistent with the interpretation advanced by Blum et al. METHODS Six baboons (Papio papio) were used in this experiment. All had been subjects in an