480 
.1. (4i;ay. 
Fig. 51. — Metapliase condition of an egg of E. aciitiis wliioli had 
been treated for half an hour with 50 c.c. sea-water + 7 c.c. 2i M. 
NaCl. The spindle is ahnornially narrow. 
Figs. 52-61. — Mitotic figures of eggs of E. acutrrs treated with 
50 c.c. sea- water -|- 15 c.c. 2^ M. NaCl for half an hour. 
Fig. 52. — Chromosomes within nuclear membrane ; no vesicles. 
Fig. 53. — A nucleus in the same phase as fig. 52 but with vesicles. 
The large vesicle looks as though it might have been formed from 
more than one centre. 
Fig. 54. — Nucleus in a slightly earlier stage than figs. 52 and 53, 
but with two well-formed vesicles. 
Fig. 55. — A slightly later stage than fig. 53. 
Figs. 56 and 57. — Prophases. Nearly all fhe chromosomes show 
evidence of giving rise to vesicles. 
Fig. 58. — Prophase. The chromosomes are not distinguishable from 
one another, being very irregular in shape, and have given rise to small 
iiTegular masses of chromatin. 
Fig. 50. — Slightly later stage than figs. 56 or 57. Five or six vesicles. 
Fig. 60. — Similar mitotic phase showing seven vesicles. 
Fig. 61. — Iri-egulai- anaphase with a very large vesicle which is very 
faintly stained and contains small granules at its peripheiy. 
PLATE 27. 
Figs. 62-71. 
Fig. 62. — Chromosome group from a spindle of an egg of E. escu- 
lentus, Series C. All the chromosomes are abnormally swollen, and in 
the right-hand grouj) is a large, irregular mass of chromatin. (Drawn 
under ocular 4, 2 mm. oil-immei’sion objective.) 
Fig. 63. — The chromosomes of fig. 21 drawn under higher magnifi- 
cation. Cent., centrosome. 
Figs. 64-66. — Chromosomes from eggs of E. acutus. Series B. 
Fig. 64. — Chromosome groups of an egg, showing thirty-four and 
thirty-five chromosomes at the two ends of the spindle, with three 
chromosomes and two vesicles omitted, thus making seventy-six 
elements in all. [Magnification oc. 4, objective 
Fig. 65. — Chromosome groups from a similar egg to the above, show- 
ing thirty-three chromosomes at each end and five omitted vesicles. 
