[Electron microscopical investigations on lichens : II. Substructure of Trebouxia-phycobionts]

The substructure in the phycobionts of the genus Trebouxia from different lichens is analysed. In the group Trebouxia I and Trebouxia II a further classification according to the differentiation of the chromatophores and their pyrenoids can be made. Trebouxia I: 1. Very long thylakoids are piled together. A few thylakoids curve through the pyrenoid. 2. The thylakoids are arranged like grana- and stromathylakoids in higher plants. In the pyrenoid the thylakoids are extended to "canals". Trebouxia II: 1. Long thylakoids are packed very close together. A few of them pass through the pyrenoid in regular intervals. 2. The thylakoids are single or in piles. In the pyrenoid the thylakoids are again extended to "canals". 3. The thylakoids are enlarged to vesicles which extend into the pyrenoid in the same form. 4. The thylakoids show all different forms of the above mentioned differentiations.In the different types of chromatophores there are always a large number of osmiophilic plastoglobuli in the pyrenoid matrix. It is discussed whether they are a reservoir in the lipid metabolism of the lichens.