When human lymphocyte cultures are exposed to EB (10μg/ml) for 2 hr prior to fixation, there is a marked increase in frequency of early mitotic cells, possibly due to the prolongation of the prophase-metaphase transition. This procedure may serve as a simple method for obtaining a large number of cells with extremely elongated chromosomes, which would permit a great precision of human chromosome analyses.
Two differently experienced groups of mice were trained to jump from a stage of various height down to a botto m platform where food was placed as a reinforcer. The richly experienced mice were demonstrated to behave boldly and to get skilled in jumpingdown in comparison with the poorly experienced ones.