322 s. HATTA : 



the structure (cd.) at the proximal portion of the Literal plate is 

 almost the same as that on the right side just described, although 

 it is here somewhat weaker in development than there. The section 

 represented in fig. 10 intervenes between the two mentioned above ; 

 in this section, the structure in question {cd.) is weakest in develop- 

 ment, consisting of four or five cells only. In the left half of fig. 15 

 which represents the section through the intersomitic portion be- 

 tween the sixth and seventh somites, there is found no structure 

 to be compared with the cord mentioned above, the proximal 

 edge of the lateral plate [x) being of the same condition as that 

 in figs. 4 and 7. In fact, the cord appears after the complete 

 separation of the Anlage from the myotome, and ivhen it is first 

 established, the nearer the plane of a section to the Anlage either 

 anterior or posterior, the thicker the cord. For instance, of the 

 above three sections (tlie left side of Figs. 9-11), the middle 

 (fig. 10) is the weakest. But this unequal development of the 

 cord is soon made even by its growth as seen in the case of the 

 cord between the Anlagen first and second (the right side of 

 figs. 9 and 10). 



The history of this cord as given above shows that it has doubt- 

 less the genetic relation with the Anlage of the pronephros. In 

 early stages, no such structure is found in the intersomitic portion, 

 but it becomes established one after the other with the develop- 

 ment of the Anlagen. The cord is in section, thickest near 

 the Anlage and weakest in the midway between two consecutive 

 Anlagen, when it is first established. These facts give naturally 

 an impression that it is growing out of the two consecutive An- 

 lagen backwards and forwards and these two growing ends meet 

 at some point in the midway between these two Anlagen, finally 

 to fuse together. This ])oint of meeting is, I think, indicated by 



