Zur Frage einer Neubildung von Mitochondrien aus Plastiden

Summary In the cells of the foot of young sporophytes ofPolytrichum commune, plastids form buds which may separate entirely from the mother plastid. In ultra-thin sections these bodies may be easily mistaken for mitochondria. However, with the silver staining method ofMarinozzi, the matrix of these bodies has the same density as the matrix of the plastids and is markedly less dense than the matrix of the mitochondria. Similarly, after silver staining the envelope of these bodies resembles the plastid envelope and is distinctly different from the mitochondrial envelope. Thus, there is no evidence that mitochondria originate from plastids, as some authors believe.