miracidium of Megalodiscus temperatus from the rectum of Rana pipiens. This section has captured one of the two flame cells in longitudinal section, showing the nucleus to the far right, a packed layer of mitochondria in the middle, and section the ciliary cone to the left.  The cone of cilia has been caught in mid-undulation and therefore the cilia are not cut longitudinally.  The black material near the top of the photo is glycogen.  Near the bottom of the photo can be seen secretory bodies of the secretory sac.  The 8 dark granules near the bottom are artifacts of the lead citrate staining.  34,00x.