EARLY DEVELOPMENT OF GRANTIA COMPRESSA. 297 



Fig'. 21. Blastula just before differentiation of flagellated hemisphere (see PL 22. fig. 27). 

 The fine mitochondria, still visible but staining less well, lie around the nuclei. 

 The yolk is not shown. At GAM is a granular amceboid cell. Judging from 

 the contour of this blastula, the future flagellated hemisphere will differentiate 

 on the right, and away from the nearest collar-cell. Oh.K., I.H. 



Fig. 22. Younger blastula showing even segregation in each blastomere of yolk-spheres and 

 mitochondria. The ectoplasm is slightly larger in quantity on the right than on 

 the left. The yolk-spheres have been added from another preparation prepared 

 by Kopsch's method. Oh.K., I.H., & K. 



Plate 22. 



Figs. 23, 25, & 26. Parts of flagellated gastral epithelium, showing at PC and OGA two 

 stages in metamorphosis of collar-cell into oogonium. Oh.K., I.H. 



Fig. 24. Part of flagellated gastral epithelium showing immigration inwards of collar-cells, 

 a\, a 2, & a 3, into the mesoglea. Ch.K., I.H. 



Fig. 27. Differentiating amphiblastula, showing future flagellated cells (FC) and future 

 lower and granular cells (GCX). At OTE is a young oocyte in growth-stage. 



Plate 23. 



Figs. 28 & 32. Two amphiblastula larvae, for description of which see page 266. Ch.K., 

 I.H.. and Ch.K., Alt. 



Fig. 29. Maternal nutrient capsule-cell (LGC in fig. 28), showing irregular and numerous 

 mitochondria (M). Ch.K., I.H. 



Fig. 30. Inner amceboid granular cell (GUM in fig. 28) showing dense numerous mito- 

 chondria. 



Fig. 31. Granular cell (GC in fig. 28) showiug scattered yolk-spheres (Y), mitochondria (M), 

 and what are possibly Golgi elements at GX. Ch.K., I.H. 



Fig. 32. (See legend to fig. 28.) 



Fig. 33. Fligellated cell or histocyte showiug four cytoplasmic elements. Mitochondria 

 (M), yolk (Y), Golgi apparatus (GAP), and outer "yolk" granules at OG. 



