IG Art. 3.— Naohicle Yatsu : 



VI. Summary. 



Observational part : 



1. The ctenophore egg is composed of (a) the outer homo- 

 geneous laj^er, (b) ectoplasm and (c) entoplasm. 



2. The outer homogeneous layer is homologous with 

 Ziegler's " hj^aline Aussenschicht " of the echinoderm egg. 



o. The ectoplasm is an alveolar plasm and rays may be 

 formed in it. 



4. The ectoplasm is phosphorescent. 



5. The sperm-rays and pole-rays of the first division enter 

 the entoplasm, the alveolar walls of the latter taking a radial 

 arrangement. 



6. Polyspermie eggs may clenve Jiomially. 



7. Cleavage is not strictly unilateral, the furrow being formed 

 in the micromere region. 



8. Fine spinning of the homogeneous layer can be seen at 

 entrance and at the bottom of the cleavage furrow. 



9. In the "cleavage head" radiations are seen in the 

 homogeneous outer layer and ectoplasm, but they do not extend 

 into the entoplasm. 



10. Beneath the "cleavage head" tlie ontoplasmic alveoles 

 are considerablj^ compressed. 



11. The micromeres consisting almost entirely of the 

 ectoplasm cleave very similarl}^ to the Avhole egg. 



12. In the beginning of each cleavage, ectoplasmic accumula- 

 tion is seen at the macromere pole. Towards the end of cleavage, 

 an accumulation appears in the micromere region. 



Experimental Part : 



13. Enucleated fragments destitute of the " cleavage head " 

 not manifest any division activity. 



14. The cleavage plane is not predetermined in the egg. 



15. An enucleated piece provided with the "cleavage head" 

 divides by itself without the aid of either nucleus or centrosome. 

 Nor is the ray system necessary for the cleavage of enucleated 

 pieces. 



