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Sibling conflict is a fairly routine, even commonplace interaction in most families with young children. Disputes may occur over property, the progress of play or the harm children do to one another. As issues arise, parents often find themselves at the center of their childrenk -Utes.Our research over the past eight years has focused on observations of conflicts between young siblings, how parents become involved in these encounters, what they do to uy to help the children settle their differences, and what children might learn about family life from the interventions of their parents. Developmental psychology provides three important models that we have applied to our examinations of pmnts' mles in their childm's conflicts. First, there is Piaget's well-known position (1932) that parents actually impede their children's understanding of morality which develops instead through interaction with agemates. According to Piaget, mutual respect between equals enables children to comprehend that justice based on reciprocity is essential to preserving cooperative relationships. In contrast, parents endorse contradictory rules that are not well understood by their children. More important, because these rules derive their force from the parent's authority and are thus external to the child, they are antithetical to a morality based on the free and mutual acceptance of moral pmaples. According to Piaget: "Resting as it does on equality and reciprocity, justice can only come into being by free consent. Council of Canada. We are grateful to the families who participated in the study and to those who assisted in collecting and manscribing the data.

SUMMARYAn outbreak of salmonellosis in calves was monitored for persistence of Salmonella typhimurium excretion in faeces and the effect of treatment with apramycin. Prior to treatment apramycin-resistant Escherichia coli were present but all S. typhimurium isolates were sensitive. Following the treatment of six calves with apramycin, apramycin-resistant S. typhimurium were isolated from two treated calves and one untreated calf. Plasmid profiles of E. coli and S. typhimurium were compared and plasmids conferring resistance to apramycin and several other antibiotics were transferred by conjugation in vitro from calf E. coli and S. typhimurium isolates to E. coli K-12 and from E. coli to S. typhimurium. The plasmids conjugated with high frequency in vitro from E. coli to S.

Because Aspergillus is an opportunist pathogen it seems likely that affected birds were immunosuppressed. This may have occurred during the breeding season which in this species is highly stressful. The presence of fungal material in bronchial exudate and the occurrence of the disease in mates, raises the possibility that aspergillosis in hihi may be contagious.