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H. L. WIEMAN 



least, or practically absent, the notochord had been cut and 

 moved as a part of the transplant, whereas in all cases where the 

 notochord was left intact marked ventral bending occurred. 

 The principal agents in producing the bent axis are the trans- 

 planted neural tube and somites. 



Fig. 2 Embryo G9. Operated April 16. E, April 30; F, May 4; G, May 7; 

 H, May 17;/, May 26. 



Another general effect of the operation was the underdevelop- 

 ment of the gills, which never became as large and bushy as those 

 of the controls. No special effect was produced on the develop- 

 ment of the forelimbs, although many of the operations were 

 made in the region of their nerve supply. 



Figure 3, A, shows the appearance of embryo T. E. 1, eight 

 days after the operation. In the sagittal section, B, the trans- 



