Preventing maternal cannibalism in rats.

follow-up are also relevant to Horn's hypothesis that teachers are less likely to retain in grade or place in special classes children whom they know were in preschool programs. If this effect existed, presumably it would occur primarily in grades 1 and 2, so that the difference between treatment and control groups should be especially large at that time. Just the opposite was found; there were no significant differences in the first two grades (pooled z = .02, P = .98 at the end of grade 1; pooled z = .92, P = .36 at the end of grade 2). For all projects combined, at the end of the second grade the proportion of children classified as failing to meet school requirements was 39/515 (7.6 percent) in the treatment groups and 23/234 (9.8 percent) in the control groups. We plan to report those results in more detail in future publications. RICHARD B. DARLINGTON Department ofPsychology, Cornell University, Ithaca, New York 14865