The study was undertaken to determine the distribution of DNA, RNA, and histone in the nucleus, and thereby to clarify the nature of the peripheral layer. Whereas the endosome contains granules and a network which are definitely Feulgen-positive, the peripheral layer is only faintly so. Nevertheless, it contains histone and stains intensely red with methyl green-pyronin, and blue with toluidine blue. Ribonuclease removes nearly all its basophilic material, which is clearly RNA. Thus, the peripheral layer consists largely of chromatin.