298 IVATASE. 



EXPLANATION OF PLATE X. 



Loligo Fealei. 



All the figures in this plate have been magnified 90 diameters. Polar globules 

 have not been drawn in the figures. 



Fig. 16. Unsegmented stage of the germ-disc. There are considerable variations 

 in the size of the germ-disc in different ova. This is an unusually large one. Notice 

 that the anterior half of the germ-disc is larger than the posterior half. 



Fig. 17. a germ-disc at the midst of the first cleavage. 



Fig. 18. A germ- disc at the completion of the first cleavage furrow. 



Fig. 19. A germ-disc at the midst of the second cleavage. 



Fig. 20. A germ-disc at the conclusion of the second cleavage. Gaping of the 

 first cleavage furrow at the anterior and posterior margin of the blastoderm in this 

 figure as well as in the next, is produced by the pressure of the cover-glass on the 

 convex germ- disc. 



Fig. 21. A germ-disc at the beginning of the third cleavage. Notice the differ- 

 ence in the directions of cleavage in the anterior and the posterior half of the disc, 

 as indicated by the directions of the caryokinetic axes. 



