Castle. — Cioua intestinalis. 



PLATE III. 



All Figures represent sections ; magnification, 560 diameters. 



Fig. 13. Conjugation of pronuclei, viewed in the direction of the equator of the 



first cleavage spindle. (Cf. Plate I. Fig. 6.) 

 Fig. 14. First cleavage spindle. 

 Fig 15. First cleavage nearly completed. Each of the newly formed nuclei is 



made up of two vesicles as yet incompletely fused. 

 Fig. 16. Section through one of the cells of a 2-cell stage, parallel to median plane 



of the embryo. 

 Fig. 17. Section from the same series as Fig. 16 through one of the two cells, near 



the median plane of the embryo, x, finely granular protoplasm, which 



marks the posterior-ventral side of embryo (cf. Plate VIII. Fig. 45, x), 



and is traceable up to the larval stage. 

 Fig. 18. Section through an 8-cell stage parallel to median plane of the embryo. 



