The typical RNP complexes produced in puff 2-48BC in the salivary gland chromosomes as a consequence of treatments interfering with the cellular respiratory metabolism have been found in various other cell types after treatment with 5-10- minus 2 M vitamin B6 for 4 hr. In Drosophila hydei the typical RNP complexes were present in puff 2-48BC in the nuclei of gastric caeca cells, in nuclei of cells of the imaginal (wing) discs and embryonic cells in primary culture. Similar RNP complexes were observed in a puff in D. virilis salivary gland nuclei, but not in salivary gland nuclei of D. melanogaster.