Behaviors of Nucleoli at the Growth Period of Egg Cells of a Slug (<I>Limax flavus</I>)

Behaviors of nucleoli were studied histochemically on ovotestes of Limax flavus with the following results:There are found two different kinds of nucleoli and the mode of their developments seems to be divided into three stages. The development of an eosinophile nucleolus (true nucleolus) rich in RNA is accompanied by the production of a nucleolus-associated corpuscle. The true nucleolus seems to produce the nucleolus-associated corpuscle which is surrounded with an envelope derived from the true nucleolus. Besides, it is suggested that a protein rich in arginine is formed in the internal space of nucleolus-associated corpuscle which is in contact with true nucleolus.The nucleolus-associated corpuscle, when accomplished, becomes in contact with the nuclear envelope and the eosinophile nucleolus with a basophile nucleolus.The above findings may support a view that nucleoli concern an intranuclear protein synthesis playing a special role between the nucleus and the cytoplasm.