Jenninos. — Asplanchna. 



PLATE 6. 



Fig. 44. Riglit side of the egg shown iu Figure 43, Plate 5, 27-cell stage. 



Fig. 45. Dorsal pole of the egg shown in Figures 4o and 44. 



Fig. 46. Posterior view of the egg shown in the three preceding figures. Note 



the lateral position of the asters in d^-^. 

 Fig. 47. Right anterior surface of an egg, showing the quadrants B and C in the 



sixth generation. 

 Fig. 48. Sagittal optical section of the 32-cell stage, viewed from tlie right side, 



and showing the spindles in d'^'^ and d'^-^. 

 Fig. 49. Sagittal optical section of an egg slightly older than that seen in Figure 



49, sliowing the process by which the cell t/''^ is formed at the sixth 



cleavage of the entoderm. 

 Fig. 50. Sagittal optical section of an egg a little older than that seen in Figure 



49, showing the recently divided and separating asters in d"!-^, and 

 the beginning of migration of tlie cloud of granules which lies at the 

 anterior ventral margin of the cell f/''^. 



Fig. 51. Sagittal optical section of about the same stage as that shown in Figure 



50. Tiie nucleus of f^i has moved away from the periphery of the 

 cell, and the cloud of granules is distributed between it and the small 

 cells d^-'^ and rf''^. 



Apparently there is some slight variation in regard to the changes 

 in the entoderm cell as compared with the other cells. From the 

 condition of the remaining cells of the Z> quadrant, one would infer 

 that Figure 51 is younger than Figure 50, though the migration of 

 the cloud of granules is more advanced. 

 Fig. 52. Transverse optical section of the egg shown in Figure 51, through the 

 region marked in Figure 51 by the cell d^-^. The section is viewed 

 from the ventral side. 



