In sexually mature male and femaleRana temporariaL. frogs of similar body length caught in their natural habitat in seven periods of their life, the nuclear volume was measured in subfornical organ (SFO) neurocytes containing lipofuscin pigment (LFP). Content of pigment was also determined. The nuclear volume in SFO neurocytes containing LFP as well as the content of pigment were found to undergo a distinct fluctuation in thecourseof the year. The largest volume of the nuclei was observed during the period immediately preceding the breeding period in males and females (1st decade of March), and the lowest volume in the middle of the period of active life (2nd decade of July). Analogous changes in the content of lipofuscin were observed in the course of the year. The problem is discussed whether lipofuscins, aside from their metabolic character, also play a part in storage and secretory function in amphibians.