ABSTRACT
1. Comparisons were made of the results of searches within and among different species of organisms for sequence matches between transfer RNAs and ribosomal RNAs. The purpose was to determine whether the matching sequences might result form selection acting on the two RNAs within a common cellular environment. 2. The results indicate that most matches do not reflect such selection. The matches described we more frequent than those found in searches among randomized sequences and the frequency of intraspecific matches was not significantly higher than that of interspecific matches. 3. The matches ara thought to identify conserved vestiges of a molecule or molecules ancestral to both classes of RNAs (Bloch, D.P., McArthur, B. and Mirrop, S (1985), BioSystems, 17:209-225). The matching sequences are interpreted as homologies