4 ART. 11. — S. HATTA. 



to the surface of the ovum, now stands apart at some distance 

 from the latter. Seen from the lateral side, the ovum appears 

 deeply constricted in the direction of the groove. For the 

 sake of convenience this groove will be called the boundary 

 groove from its position. 



One might suppose that the groove just referred to repre- 

 sents an early trace of the blastopore, as was probably so 

 assumed by Max Schultze.^^ The present author came previously 

 to the same erroneous assumption. The blastpore, however, appears 

 later, as will become clear from the following description. 



At a time when the arms of the groove nearly reach the 

 opposite point of the ovum, a second depression {Figs. 5a and 5b, 

 hp.) appears in the same meridional zone as, and a little below, 

 the first one ; this constitutes tJie filmst rudiment of the blastopore. 

 The blastoporic depression is likewise transverse in position 

 {Figs. 5a, 5b, Q>b, and 6c, bp.) ; it is, however, not hollowed out 

 evenly on the bottom in the shape of a pulley's groove, as in the 

 case of the boundary groove {Fig. Za, bg.), but is pushed forwards, 

 so that in section the bottom presents an acute angle in the 

 deepest part of the depression ; thus producing dorsally a steep 

 ridge overhanging the depression itself, while ventrally it is 

 shallowed and loses itself on the surface of the opaque hemisphere. 

 The whole of this crescentic groove appears like a nail-mark left 

 on a soft body such as dough. 



In the above statements I have set aside an important 

 point which is, however, full of significance. Shortly after the 

 appearance of the boundary groove, it is seen that the rounded 

 base of the ovum, on which this rests in the position given in Figs. 

 1, 2, &c., shows a more or less' flattening of the surface near the 



1) loc. cil. p. l.'î. 



