20 AKT. 11. — S. HATÏA. 



appears not al the junction line, i. e., not at the bouiulary Ix'twecn 

 the microraerie epithelium and the macromeric cell-mass, out in 

 the macromeric part itself. In younger stages {Fi(j. 14), the upper 

 limit of the conical eminence is represented by the boundary 

 groove which there coincides with the junction line. When the 

 curvature of the boundary groove takes place {p. 11), the groove 

 in the dorsal part shifts a little further forwards ; nevertheless, 

 the conical eminence is formed almost entirely of the macro- 

 meric [)art (/''iff- 1'3). Therefore, decidedly macromeric must 

 be the flat field which forms the lower slope of the eminence; 

 and it is this field which is converted into the blastoporic notch 

 (Fif/- 16). The junction-line corresponds, in the stage spoken 

 of {M(/- 10), to the free margin of the dorsal blastoporic lip(*), 

 as it may now be called ; this line is, however, by no means 

 distinct nor sharply defined. 



Lastly, as an ell'ect of the actual (visible) invagination of th{> 

 macromeric part, the segmentation cavity is obliterated to a 

 certain extent and consequently assumes a new outline [Fiff. 16. 

 .5. c). The conical eminence suffers a greater alteration : it is 

 changed into a less conspicuous elevation which lies between the 

 blastopore and the boundary groove, its original conspicuous part 

 having been pushed in, forming the walls of the invagination. 

 The boundary groove (/^.y.) which has ))ecome, as stated above, 

 manifest by the growing prominence of the eminence, becomes 

 likewise inconspicuous. It is no doubt these changes which caused 

 (îoette to state : " Sie (the eminence) verstreicht aber sehr 

 l)ald, nachdem gerade unter ihr, also zwischen dem Ilande der 

 Keimhöhle und dem Gegenpol, die erste Andeutung des Urdarmes 

 sichtbar geworden ist."'' I can» not Init wonder at his keen 



1) loc. cil; p. 2. 



