10 8 13 8 13 8 14 7 15 7 13 7-1/2 11 8 16 5-1/2 12 7 10 7 15 6 13 6 12 7 The numbers given refer to degrees on my micrometer scale. Since it is the ratio alone which it is necessary to call attention to, the numbers are not reduced to decimals of a millimeter. Each degree of my scale is equal, however, with the object glass employed, to .002 Mm. This series brings out the result I have just mentioned with great clearness. In one case we find a cell has three times the diameter of the nucleus 16 : 5-1/2; in another case 10 : 8, the nucleus has only a slightly smaller diameter than the cell. The irrationality of the ratio is fairly shewn in some of my figures, though none of the largest cells with very small nuclei have been represented. The nuclei are granular, and stain fairly well with hæmatoxylin. They usually contain a single deeply stained nucleolus, but in many cases, especially where large (and this independently of the size of the cell), they contain two nucleoli (Pl. 12, figs. 14_c_ and 14_d_), and are at times so lobed as to give an apparent indication of commencing division. A multi-nucleolar condition of the nuclei, like that figured by Götte[225], does not appear till near the close of embryonic life, and is then found equally in the large ova and in those not larger than the ova which exist at this early date. Footnote 225: _Entwicklungsgeschichte der Unke_, Pl. 1, fig. 8.