'Nussbaum [note: 'Arch. f. Mik. Anat., Bd. XVI. s. 543, 1879.'] suggests that the transition-cells which I describe are different from the darkly-stained cells described by him; a comparison of the figure 1 of his first communication with mine [note: 'Op. cit.'], and of the figure 1 of his second communication [note: 'Arch. f. Mik. Anat., Bd. XV. s. 119, 1878.'] with my fig. 2, Plate VIII., adjoined to this Paper will, I think, shew that we are dealing with the same cells.' (272-273)