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Two neighboring groups of masked titi monkeys (Callicebus personatus personatus) were observed for nearly 240 hr over a 5-mo period. Minimum home range estimates for the groups were 10.7 and 12.3 ha; daily path length averaged 1 km. Each group shared a minimum of nearly 20% of its range with neighbors, and encounters between groups were rare and exclusively vocal. There was no strong evidence that titis called at the edge of their ranges or used non-overlap areas more intensively. Masked titis at this site were therefore not markedly territorial, in contrast to other descriptions of this genus. However, this study was carried out at a time of unusually low rainfall, which may have influenced behavior. Further longer-term studies of adjacent groups are therefore required to assess environmental, specific, and subspecific factors affecting territoriality in this genus.

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Food sharing behavior was investigated by studying 10 captive black lion tamarin (Leontopithecus chrysopygus) infants (six litters) between the ages of four and 26 weeks. The frequency of sharing by parents in response to infant begging increased steadily from the age of five to nine weeks, but then declined gradually, although infants were still receiving food even at 26 weeks. Until the age of 15 weeks, infants received more food items by transfer from other group members than they did from self-feeding. Thereafter, self-feeding predominated. Offering of food by adults without prior infant begging occurred at low frequencies (5.3% of items transferred) and ceased at 20 weeks of age. Begging success (the proportion of infant begs which resulted in food sharing) remained relatively constant, averaging 65%. In common with other lion tamarins, black lion tamarins appear to continue to share food with infants well after weaning, and until at least six months of age.

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A doctor prescribes a beta-blocker to calm a patient's muscle tremors, even though the Food and Drug Administration (FDA) has only approved the drug for use in lowering blood pressure. A physician recommends that a patient wear a nicotine patch as a treatment for colitis. A pediatrician prescribes a drug that has been approved for adult use only. Such "off-label" prescriptions are increasingly common--and legal.

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Aye-ayes possess highly adapted hands, using their specialized third digits to investigate potential food sources by tapping and the third or fourth digits to transfer food to the mouth. Observations were conducted on 11 captive aye-ayes (10 wild-caught; 1 captive-bred) following presentation of food or novel objects, and hand use for holding, tapping and digit-feeding was scored. Eight of the individuals showed significant hand preferences for one or more of the 3 measures, although there was no consistent pattern. These preliminary results are compared to those from other lemur species.

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The ability of 6 captive aye-ayes (Daubentonia madagascariensis) to discriminate scents from conspecifics of different age-sex classes was tested. The animals were presented with either unscented logs or logs that had been placed in: (1) their own cage, (2) the cages of adult males or (3) the cages of adult females with female offspring. Responses to the logs, measured by approaching, proximity, tapping, gnawing, sniffing, scent marking and vocalizations, were recorded for 30 min following presentation. Logs from females with offspring provoked the highest responses, and immature aye-ayes investigated logs more than adults of either sex. These results suggest that, as in many other prosimians, olfaction plays an important role in the communication systems of aye-ayes.

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Food-sharing behaviour was observed in 9 captive families of cotton-top tamarins (range 4-14 individuals per group), during meals of fresh fruit. Food was transferred to infants by their parents and older sibs in response to begging, and was also offered to them without prior solicitation. Older, mature, reproductively suppressed individuals shared more than young immature monkeys. Infants in larger families received more food than those in smaller ones, though individuals in smaller families shared more. Transfer to infants increased to a maximum at 12 weeks of age and then declined gradually. At one year of age they no longer received food from others. Food sharing by older siblings is a form of helping behaviour which may increase their inclusive fitness, and benefit parents, both directly, by reducing the costs they incur in rearing young, and indirectly, by increasing the amount of food available to infants.

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Two children developed profound visual loss in the eye being patched full time because of strabismic amblyopia in the fellow eye. The first had been patched for 13 days at age 18 months. Complete resolution was noted on the 40th day of reverse occlusion. The second had been patched for 1 month at age 9 months. After 3 months without treatment, reverse occlusion was instituted and was continued for 3 years. Mild amblyopia persists in both eyes of the second child. Although rare, occlusion amblyopia can occur in young children being patched full time. We usually avoid full-time occlusion and monitor patients at intervals at least as frequent as 1 week per year of age.

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Anterior segment ischemia (ASI) is a potentially blinding complication of extensive eye muscle surgery. Eyes have been described with this complication following surgery on as few as two rectus muscles, especially in patients with thyroid dysfunction or other medical illnesses. In an attempt to assess the risk of ASI, we have reviewed the records of 34 eyes in 26 patients who underwent surgery on three or four rectus muscles. Seven eyes of six patients with thyroid ophthalmopathy which underwent two-or three-muscle surgery were also studied. Evidence of clinically significant ASI was apparent in only one patient during a follow-up period of seven months to eleven years. This case was mild and no visual loss resulted. Our findings suggest that surgery on three or four rectus muscles in healthy patients is probably safe when performed in a staged fashion.

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