376 WHEELER. 
DESCRIPTION OF PLATE XVI. 
Blatta germanica. 
Fic. 23. Cleavage nucleus dividing. a, points to the ventral contour. The nucleus 
in this egg had moved out into the granular yolk some distance. 
Fic. 24. Two nuclei; @, seen in lateral, and 4, in polar view, from an egg contain- 
ing 4 nuclei in the metakinetic stage of division. 
Fic. 25. Ventral third of a transverse section of an odthecal egg; @ and 4, cells 
which have just reached the surface. The amceboid cell in the interior is on its way 
to the surface. 
Fic. 26. Corresponding section of the somewhat older egg (Fig. 36). @, a 
group of cells formed by tangential akinesis from one of the nuclei, like @, Fig. 25. 
Fic. 27. Ventral third of a transverse section of an egg in the blastoderm stage; 
6 days old. 
Fic. 28. Ventral third of a transverse section. Blastoderm contracting. At 2’, 
yolk nucleus being given off; at «, one which has sunk deep into the yolk. 
Fic. 29. Transverse section through e, of an embryo like the one represented in 
Fig. 43. v, yolk-cell; sd, mesoderm; ecd, ectoderm. 
Fic. 30. Transverse section through e! of the embryo 43. a@, amnion; 57, serosa; 
ecd, ectoderm; msd, mesoderm; 7, yolk-cell. 
Fic. 31. Transverse section through the point fc/ of Fig. 41. ecd, ectoderm; 7z, 
yolk-cell; #zsd, mesoderm. 
Fic. 32. Transverse section through a point a little in front of as of Fig. 43. am, 
amnion; sv”, serosa; ecd, ectoderm; msd, mesoderm; 7v, yolk-cell. « 
Fic. 33. Surface view of blastoderm, showing the binucleolate nuclei. 
Fic. 34. Enlarged view of syncytium «, in Fig. 36; showing the unequal size of 
the nuclei. 
Fic. 35. @ and c, surface nuclei in akinetic division from an egg in the same stage 
as Fig. 36; 4, serosa nucleus in akinesis from a much older egg. 
Fic. 36. Surface view of an egg shortly after the nuclei have begun to appear 
on its surface. c, cephalic end; s, sinus; v, ventral surface; dd, dorsal surface; x, a 
group of nuclei like that seen in section at a, in Fig. 26. 
Fic. 37. Surface view of an egg in the blastema stage; 4 days old. 
Fic. 38. Long. sect. along the carina cz, of Fig. 41; through the depression 4. 
sv, serosa; 4, depression; ecd, ectoderm; msd, mesoderm; 7, yolk-cells. 
