30O WATASE. 



EXPLANATION OF PLATE XL 

 Loligo Pealei. 



All figures in this plate have been magnified 65 diameters. 



Fig. 22. A blastoderm consisting of 8 cells, 4 in front, and 4 behind the second 

 furrow of cleavage. All the cells in front are larger than those behind. 



Fig. 23. A blastoderm consisting of 12 cells. 



Fig. 24. A blastoderm consisting of 18 cells. All the segments in front of the 

 second furrow of cleavage are more advanced than those behind it. 



Fig. 25. A blastoderm consisting of 22 cells. 



Fig. 26. A blastoderm which has just entered into the 32-cell stage. A wide cleft 

 in the left side of the blastoderm, 2', corresponding to the second furrow of cleavage, 

 was produced by the separation of the adjacent segment due to the pressure by cover- 

 glass. 



Fig. 27. A blastoderm consisting of 32 segments, with all the segments in the 

 front half of the blastoderm in the midst of division, while the nuclei in the posterior 

 half are in a " resting " condition. A group of 6 inner cells, and a pair of marginal 

 cells along the first cleavage furrow, in the posterior half of the blastoderm, present 

 the characteristic appearance of this stage. As the later stages will show, these 

 groups of cells make the slowest growth in the whole blastoderm. 



