Describes three experiments which investigated the behavior of "Colisa fasciata" males in full breeding condition subjected to competition for nest sites and a single female. Concludes that for these fish territorial dominance is established in a relatively short time, the period varying with the intensity of competition. (MLH)

Discusses several alternatives to the use of laboratory animals in investigating biomedical problems. Alternatives include tissue culture, use of plant and bacterial material, redesigning experiments, and construction of mathematical and computer models. (CS)