(1) The presence of one or more intra-nucleolar bodies in the columnar cells of the intestinal epithelium in the frog and cat has been demonstrated. To these inclusions the term "nucleolinus," originally introduced by Haeckel, has been applied.
(2) By a modification of the Cajal technique for the Grolgi apparatus, the nucleolinus has, in the frog's intestine, been impregnated in a perfectly specific manner.
(3) The presence of nucleolini both in karyosomes (e.g. cat)and in plasmosomes (e.g. frog) in the columnar intestinal cells shows that they are not restricted to one of these types of nucleolus.
(4) Evidence has been adduced showing that division of the nucleolus (plasmosomes) in the resting cell is in all probability accompanied by fission of the nucleolinus.
(5) During mitosis the nucleolinus has been shown apparently to divide, a portion or portions of it being distributed to each of the daughter-nuclei. This is in contrast to the behaviour of the nucleolus (plasmosome), which disintegrates during cell division.
(6) The presence of the nucleolinus has been confirmed in the columnar cells of the intestinal mucosa in both the frog and the cat by other and simpler methods than the Cajal technique.
(7) The significance of the apparent continuity of the nucleolinus has been very briefly discussed.