224 



CHILD. 



[VOL. I. 



Figure 8. 



This case, though at a later stage of development than Fig. 7, 

 resembles it. Two partial furrows appear, one on the dorsal, the 

 other on the ventral surface, corresponding exactly in position 

 and length, but entirely unconnected. The exact correspondence 

 in position and length of these two entirely unconnected furrows 

 indicates very clearly, as does the similar condition in Fig. 7, that 



the position of the furrows is 

 determined by internal condi- 

 tions, for it is difficult to under- 

 stand how two perfectly similar 

 partial furrows could arise on op- 

 posite surfaces of the body except 

 as the expression of certain internal form-producing conditions. 



The genital organs are duplicated on the left side, but the two 

 pores are approximated. The individuality of the two portions 

 is apparently not sufficient to give rise to furrows at the edge, so 

 that pores tend to appear near the middle of the edge. But the 

 furrows extend almost to the edge, and the existence of two pores 

 is undoubtedly the re- 

 sult of this position, -f 

 The right side shows 

 no trace of duplica- 



tion. 



Figure 



FIG. 9. 



This figure shows 

 three cases of partial 

 division, and in all the 

 partial furrows end 

 free and correspond 

 on the two surfaces. The partial furrows between a and b are 

 most nearly complete, extending past the middle of the body. 

 Between c and d they are shorter, and between e and f still 

 shorter. In each case the two partial segments are longer than 

 the corresponding single segment at the opposite edge, conse- 

 quently oblique furrows appear between the three sets, but, 



