The Development of Mitochondria inArumSpadix

Electron micrographs of Arum spadix cells prepared at four stages of development all showed abundant sections of mitochondria with tubular ingrowths (microvilli). At the earliest stage (when the spadix cells were still dividing) there was an average of 9 sections of microvilli per mitochondrion. In later stages of development, when the cells were growing by elongation, the number of microvilli rose to 22. It was reported earlier that the succinoxidase activity of the mitochondria of Arum spadix increased as the spadix developed, and it is now shown that the rise in enzyme activity parallels the increase in length of microvilli.