CELL DIVISION IN EGGS OF CREPIDULA. 591 



Fig. 216. Exp. 846: Egg from same experiment as the preceding; the nuclei at the vegetal pole are 

 probably derived from chromosomes which were scattered along the first cleavage spindle as in fig. 215 



Fig. 217. Exp. 822: 2 per cent. NaCl, 16 hrs., normal 8 hrs.; irregular and unequal 2d cleavage with 

 several karyomeres of varying size in each cell. 



Fig. 218. Exp. 842: 4 per cent. MgCl 2 , 5 hrs., normal 17 hrs.; the divisions of the cell body at the 2d 

 cleavage were suppressed in the left half, but two micromeres are arising in normal manner from this half ■ 

 several accessory asters are present in this half which have served to scatter the chromosomes. The right 

 half of the egg is quite normal. 



Fig. 219. Exp. 867: 8 per cent. MgCl 2 , f hr., normal 6 J hrs.; the 3d cleavage was very irregular and 

 has given rise to a large number of karyomeres, and spheres which are in division in three quadrants of 

 the egg. 



Fig. 220. Exp. 972: 2 per cent. NaCl, 16 hrs., normal 24 hrs.; second quartet formation; karyomeres 

 or polyasters in each of the cells. 



Fig. 221. Exp. 814: 2 per cent. NaCl, 1 hr., normal 17 hrs.; second quartet formation; karyomeres 

 and spheres in every cell. 



Fig. 222. Exp. 828: 1 per cent. NaCl, 2 hrs., normal 6J hrs.; second quartet formation; karyomeres 

 and polyasters in every cell. 



Fig. 223. Exp. 972: 2 per cent. NaCl, 16 hrs., normal 24 hrs.; karyomeres (and asters) in every 

 cell; all nuclei are vesicular and contain achromatin as well as chromatin. 



