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H. L. WIEMAN 



notochord at t. no. Regeneration in the notoehord is taking 

 place in the stumps; the transplanted piece appears atrophied 

 and seems to take no part in the process. F, passes through the 

 posterior hmit of the transplant. Here again the canal is missing. 

 The section also shows the overlapping ends of the regenerating 

 notochord. Posterior to this level the sections are normal. 



Fig. 15 Embryo T.R.7, transverse sections. 

 no., regenerating ends of the notochord. 



transplanted notochord; 



Therefore, the conditions found in the transverse series confirm 

 what has akeady been shown in the sagittal series of T. R. 4, 



Frontal sections afford a view of the process from still a dif- 

 ferent angle and supply further confirmation of the conclusions 

 already reached. Embryo G9 was cut into frontal sections for 

 this purpose. It is shown at the operating stage in figure 1, D. 

 Figure 2 consists of drawings of the embryos at various intervals 

 up to the time of killing, May 17th. Responses to tactile stimu- 

 lation indicated that conduction pathways were estabhshed 



