706 



Furfhermore, experiments by O. Mangold') tend to show that after 

 the conclusion of the gastrulation, i.e. when the region of the medul- 

 lary plate has already been determined, ectoderm of the ventral 

 half of the larva can still form mesoderm or entoderm. From this 

 we see that this ectoderm has not yet been determined. 



My experiments to find an answer to the question if there is 

 any relation between the determination of the polarity of the cell 

 and of its organogenetic function, were carried out in the region of 

 the future medullary plate. A more extensive investigation is required 

 for the purpose of ascertaining whether the phenomenon that the 

 determination of tiie polarity of the cell almost coincides with that 

 of the organogenetic function of the cells holds generally or onlj- 

 for the region of the medullary plate. 



In a subsequent communication 1 intend to discuss the histo- 

 physiological data regarding the ciliary movement obtained in the 

 experiments reported in this paper. 



') 0. Mangold. Verhandl. deutsch. zoolog. Gesellscb. Bnd. 27. Sept. 1922. p. 51. 



